EDBT 2026 Demo / reviewers in the wild / expert
Flora D. Salim
dblp:08/1554 · also Flora Dilys Salim, Flora Dylis Salim, Flora Salim
· DBLP profile ↗
72ranked-venue papers in the field
2as first author
52since 2021 · last 2026
0000-0002-1237-1664ORCID · verified
Domains — venue-derived; a paper can count in several
Database Systems & Data Management · 27 (1 first)Information Retrieval & Web Search · 22 (1 first)Data Mining & Knowledge Discovery · 21Knowledge Engineering, Semantic Web & Information Systems · 2
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2026 | MANILA26: SIGIR 2026 Tutorial on Information Retrieval for Climate Change ImpactabstractThis three-hour tutorial uses climate change evidence synthesis as a high-stakes ''stress test'' for state-of-the-art IR and AI methods. Participants will explore why this domain, which is characterized by high levels of interdisciplinarity, multi-modal data (geospatial and time-series), and a lack of controlled vocabularies, challenges current state-of-the-art systems and active learning protocols. Through an architectural critique of agentic RAG systems and a deep dive into the ''AMOC experiment,'' the tutorial distinguishes between automated literature review and expert scientific assessment. Participants will learn to diagnose specific retrieval failure modes, such as geographic coverage bias and the ''tacit knowledge boundary,'' where human expertise remains essential. The tutorial concludes by framing a new research agenda: building unified, verifiable evidence pipelines that integrate bibliographic, geospatial, and multi-modal retrieval with rigorous provenance tracking. Maarten de Rijke, Flora D. Salim |
SIGIR | 2 |
| 2026 | When Ads Become Profiles: Uncovering the Invisible Risk of Web Advertising at Scale with LLMsabstractRegulatory limits on explicit targeting have not eliminated algorithmic profiling on the Web, as optimisation systems still adapt ad delivery to users' private attributes. The widespread availability of powerful zero-shot multimodal Large Language Models (LLMs) has dramatically lowered the barrier for exploiting these latent signals for adversarial inference. We investigate this emerging societal risk, specifically how adversaries can now exploit these signals to reverse-engineer private attributes from ad exposure alone. We introduce a novel pipeline that leverages LLMs as adversarial inference engines to perform natural language profiling. Applying this method to a longitudinal dataset comprising over 435,000 Facebook ad impressions collected from 891 users, we conducted a large-scale study to assess the feasibility and precision of inferring private attributes from passive online ad observations. Our results demonstrate that off-the-shelf LLMs can accurately reconstruct complex user private attributes, including party preference, employment status, and education level, consistently outperforming strong census-based priors and matching or exceeding human social perception at only a fraction of the cost (223× lower) and time (52× faster) required by humans. Critically, actionable profiling is feasible even within short observation windows, indicating that prolonged tracking is not a prerequisite for a successful attack. These findings provide the first empirical evidence that ad streams serve as a high-fidelity digital footprint, enabling off-platform profiling that inherently bypasses current platform safeguards, highlighting a systemic vulnerability in the ad ecosystem and the urgent need for responsible web AI governance in the generative AI era. The code is available at https://github.com/Breezelled/when-ads-become-profiles. Benjamin Tag, Hao Xue 0001, Daniel Angus, Flora D. Salim |
WWW | 5 |
| 2026 | Genomic-Informed Heterogeneous Graph Learning for Spatiotemporal Avian Influenza Outbreak Forecasting
Jing Du 0003, Haley Stone, Yang Yang 0001, Ashna Desai, Hao Xue 0001, Andreas Züfle, C. Raina MacIntyre, Flora D. Salim |
WWW | 8 |
| 2026 | Mining Citywide Dengue Spread Patterns in Singapore Through Hotspot Dynamics from Open Web Data
Gaoxi Xiao, Stefan Ma, Hechang Chen, Shisong Tang, Flora D. Salim |
WWW | 6 |
| 2026 | Beyond Single Pass, Looping Through Time: KG-IRAG with Iterative Knowledge RetrievalabstractRetrieval-augmented generation (RAG) has improved large language models (LLMs) on knowledge-intensive tasks, yet most systems assume static facts and struggle when answers depend on serialized and dynamic data, like time--e.g., ordering events, aligning facts to valid intervals, or planning actions under evolving conditions. This paper presents Knowledge-Graph Iterative Retrieval-Augmented Generation (KG-iRAG), a framework specialized for temporal reasoning. KG-iRAG couples a time-aware planner with a knowledge graph (KG) to iteratively fetch and compose evidence along a temporal axis. Concretely, it (i) represents events and facts with explicit timestamps and validity intervals; (ii) propagates temporal constraints through iterative retrieval using operators; and (iii) verifies temporal consistency while refining intermediate hypotheses, enabling step-by-step deduction for queries that mix knowledge retrieval with inference. Across public temporal QA benchmarks, KG-iRAG consistently improves accuracy and calibration over strong RAG baselines while reducing unnecessary retrieval through targeted, constraint-guided steps. To stress-test real-time decision queries, three application-oriented datasets (weatherQA-Irish, ~ weatherQA-Sydney, and~ trafficQA-TFNSW) are additionally constructed and tested alongside existing temporal benchmarks. The results demonstrate that injecting temporal structure into KG-driven RAG yields robust gains on multi-step, time-dependent queries, advancing the state of temporal reasoning with LLMs. Hao Xue 0001, Muhammad Imran Razzak, Flora D. Salim |
WWW | 4 |
| 2026 | Spectraformer: A Unified Random Feature Framework for TransformerabstractLinearization of attention using various kernel approximation and kernel learning techniques has shown promise. Past methods used a subset of combinations of component functions and weight matrices within the random feature paradigm. We identify the need for a systematic comparison of different combinations of weight matrices and component functions for attention learning in Transformer. Hence, we introduce Spectraformer , a unified framework for approximating and learning the kernel function in the attention mechanism of the Transformer. Our empirical results demonstrate, for the first time, that a random feature-based approach can achieve performance comparable to top-performing sparse and low-rank methods on the challenging Long-Range Arena benchmark. Thus, we establish a new state-of-the-art for random feature-based efficient Transformers. The framework also produces many variants that offer different advantages in accuracy, training time, and memory consumption. Our code is available at: https://github.com/cruiseresearchgroup/spectraformer . Duke Nguyen, Du Yin, Aditya Joshi 0001, Flora D. Salim |
ACM Trans. Intell. Syst. Technol. | 4 |
| 2025 | Dynamic Budgeted Reinforcement Learning for Fairness in Spatial-Temporal Resource AllocationabstractIn recent years, utility optimization and fairness have emerged as key objectives in spatial-temporal resource allocation systems, such as ridesharing and food delivery, attracting significant research interest due to their often conflicting nature. Systems focused solely on optimizing utility can create disparities, such as disparate earnings among rideshare drivers, leading to ethical and economic issues. Conversely, focusing solely on fairness can paradoxically reduce overall utility, resulting in a scenario where no one truly benefits. To address this, many Reinforcement Learning (RL)-based approaches have been proposed due to its capacity to generate dynamic, non-myopic allocation plans. Typically, RL-based approaches balance utility and fairness by constructing direct trade-off functions between them. However, this paper argues that in dynamic situations, the scale of the objectives may differ significantly, causing RL to overemphasize one objective at the expense of the other. To effectively address this issue, we propose formulating the challenge of balancing utility and fairness in spatial-temporal resource allocation as a Constrained Markov Decision Process. Here, fairness is treated as a constraint while utility optimization serves as the standard reward. Building on this foundation, we introduce Dynamic Budgeted Proximal Policy Optimization (DB-PPO). We demonstrate that DB-PPO outperforms existing approaches in fairness-oriented spatial-temporal resource allocations using two real-world publicly available datasets. Yufan Kang, Wei Shao 0006, Mark Andrejevic, Jeffrey Chan, Flora D. Salim |
SIGSPATIAL/GIS | 7 |
| 2025 | EpiScale: Large-Scale Simulation of Infectious Disease Based on Human MobilityabstractWe present a demonstration of a highly scalable, spatially explicit infectious disease simulation that models the spread of disease across all 220,000+ census block groups in the United States using a compartmental Susceptible-Infectious-Recovered (SIR) epidemiological framework. To achieve this unprecedented scale and resolution, our system leverages efficient sparse matrix and vector operations alongside statistical approximations of large numbers of independent random events via Poisson and Normal distributions. The resulting simulation produces realistic spatiotemporal dynamics that align with empirical patterns observed in major epidemics, including the COVID-19 outbreak. Our live demonstration at the conference will highlight the simulation's computational efficiency and interactive capabilities. Starting from the conference venue in Minneapolis, participants will be able to configure disease parameters and observe the geographic spread of infection in real time, offering both an educational and analytical perspective on pandemic modeling. Ruochen Kong 0001, Taylor Anderson 0001, David J. Heslop, Matthew Scotch, Flora D. Salim, C. Raina MacIntyre, Andreas Züfle |
SIGSPATIAL/GIS | 5 |
| 2025 | Classical Feature Embeddings Help in BERT-Based Human Mobility PredictionabstractHuman mobility forecasting is crucial for disaster relief, city planning, and public health. However, existing models either only model location sequences or include time information merely as auxiliary input, thereby failing to leverage the rich semantic context provided by points of interest (POIs). To address this, we enrich a BERT-based mobility model with derived temporal descriptors and POI embeddings to better capture the semantics underlying human movement. We propose STaBERT (Semantic-Temporal aware BERT), which integrates both POI and temporal information at each location to construct a unified, semantically enriched representation of mobility. Experimental results show that STaBERT significantly improves prediction accuracy: for single-city prediction, the GEO-BLEU score improved from 0.34 to 0.75; for multi-city prediction, from 0.34 to 0.56. Yun-Zhi Liu, Haokai Tan, Rushi Kanjaria, Lihuan Li, Flora D. Salim |
SIGSPATIAL/GIS | 5 |
| 2025 | A Probabilistic Framework for Imputing Genetic Distances in Spatiotemporal Pathogen ModelsabstractPathogen genome data offers valuable structure for spatial models, but its utility is limited by incomplete sequencing coverage. We propose a probabilistic framework for inferring genetic distances between unsequenced cases and known sequences within defined transmission chains, using time-aware evolutionary distance modeling. The method estimates pairwise divergence from collection dates and observed genetic distances, enabling biologically plausible imputation grounded in observed divergence patterns, without requiring sequence alignment or known transmission chains. Applied to highly pathogenic avian influenza A/H5 cases in wild birds in the United States, this approach supports scalable, uncertainty-aware augmentation of genomic datasets and enhances the integration of evolutionary information into spatiotemporal modeling workflows. Haley Stone, Jing Du 0003, Hao Xue 0001, Matthew Scotch, David J. Heslop, Andreas Züfle, C. Raina MacIntyre, Flora D. Salim |
SIGSPATIAL/GIS | 8 |
| 2025 | GenUP: Generative User Profilers as In-Context Learners for Next POI Recommender SystemsabstractTraditional Point-of-Interest (POI) recommendation systems often lack transparency, interpretability, and scrutability due to their reliance on dense vector-based user embeddings. Furthermore, the cold-start problem—where systems have insufficient data for new users—limits their ability to generate accurate recommendations. Existing methods often address this by leveraging similar trajectories from other users, but this approach can be computationally expensive and increases the context length for large language model-based methods, making them difficult to scale. To address these limitations, we propose a method that generates natural language (NL) user profiles from large-scale, location-based social network checkins, utilizing robust personality assessments and behavioral theories. These NL profiles capture user preferences, routines, and behaviors, improving POI prediction accuracy while offering enhanced transparency. By incorporating NL profiles as system prompts to large language models, our approach reduces reliance on extensive historical data, while remaining flexible, easily updated, and computationally efficient. Results demonstrate that our approach consistently outperforms baseline methods, offering a more interpretable and resource-efficient solution for POI recommendation systems. Our source code is available at: https://github.com/w11wo/GenUP/. Wilson Wongso, Hao Xue 0001, Flora D. Salim |
SIGSPATIAL/GIS | 3 |
| 2025 | STOAT: Spatial-Temporal Probabilistic Causal Inference NetworkabstractSpatial-temporal causal time series (STC-TS) involve region-specific temporal observations driven by causally relevant covariates and interconnected across geographic or network-based spaces. Existing methods often model spatial and temporal dynamics independently and overlook causality-driven probabilistic forecasting, limiting their predictive power. To address this, we propose STOAT (Spatial-Temporal Probabilistic Causal Inference Network), a novel framework for probabilistic forecasting in STC-TS. The proposed method extends a causal inference approach by incorporating a spatial relation matrix that encodes interregional dependencies, enabling spatially informed causal effect estimation. The resulting latent series are processed by deep probabilistic models to estimate the parameters of the distributions, enabling calibrated uncertainty modeling. Experiments on COVID-19 data across six countries demonstrate that STOAT outperforms state-of-the-art probabilistic forecasting models in key metrics, particularly in regions with strong spatial dependencies. By bridging causal inference and geospatial probabilistic forecasting, STOAT offers a generalizable framework for complex spatial-temporal tasks, such as epidemic management. Yang Yang 0001, Du Yin, Hao Xue 0001, Flora D. Salim |
SIGSPATIAL/GIS | 4 |
| 2025 | XXLTraffic: Expanding and Extremely Long Traffic Forecasting beyond Test AdaptationabstractTraffic forecasting is crucial for smart cities and intelligent transportation initiatives, where deep learning has made significant progress in modeling complex spatio-temporal patterns in recent years. However, current public datasets have limitations in reflecting the distribution shift nature of real-world scenarios, characterized by continuously evolving infrastructures, varying temporal distributions, and long temporal gaps due to sensor downtimes or changes in traffic patterns. These limitations inevitably restrict the practical applicability of existing traffic forecasting datasets. To bridge this gap, we present XXLTraffic, the largest available public traffic dataset with the longest timespan collected from Los Angeles, USA, and New South Wales, Australia, curated to support research in extremely long forecasting beyond test adaptation. Our benchmark includes both typical time-series forecasting settings with hourly and daily aggregated data and novel configurations that introduce gaps and down-sample the training size to better simulate practical constraints. We anticipate the new XXL-Traffic will provide a fresh perspective for the time-series and traffic forecasting communities. It would also offer a robust platform for developing and evaluating models designed to tackle the extremely long forecasting problems beyond test adaptation. Our dataset supplements existing spatio-temporal data resources and leads to new research directions in this domain. Du Yin, Hao Xue 0001, Arian Prabowo, Shuang Ao, Flora D. Salim |
SIGSPATIAL/GIS | 5 |
| 2025 | FairDRL-ST: Disentangled Representation Learning for Fair Spatio-Temporal Mobility PredictionabstractDeep spatio-temporal neural networks are increasingly used in urban computing, impacting critical infrastructure such as public transport, emergency services, and traffic systems. While most methods focus on accuracy, fairness has become a key concern as biased predictions can disadvantage specific demographic or geographic groups, reinforcing inequalities. We propose FairDRL-ST, a disentangled representation learning framework for fair spatio-temporal prediction, with a focus on mobility demand forecasting. By combining adversarial and disentangled learning, our approach separates sensitive attributes and achieves fairness in an unsupervised manner with minimal performance loss. Experiments on real-world urban mobility datasets show that FairDRL-ST reduces fairness gaps while maintaining competitive predictive accuracy against state-of-the-art fairness-aware methods.1 Sichen Zhao, Wei Shao 0006, Jeffrey Chan, Ziqi Xu 0001, Flora D. Salim |
SIGSPATIAL/GIS | 5 |
| 2025 | Foundation Models for Spatio-Temporal Data Science: A Tutorial and SurveyabstractSpatio-Temporal (ST) data science, which includes sensing, managing, and mining large-scale data across space and time, is fundamental to understanding complex systems in domains such as urban computing, climate science, and intelligent transportation. Traditional deep learning approaches have significantly advanced this field, particularly in the stage of ST data mining. However, these models remain task-specific and often require extensive labeled data. Inspired by the success of Foundation Models (FM), especially large language models, researchers have begun exploring the concept of Spatio-Temporal Foundation Models (STFMs) to enhance adaptability and generalization across diverse ST tasks. Unlike prior architectures, STFMs empower the entire workflow of ST data science, ranging from data sensing, management, to mining, thereby offering a more holistic and scalable approach. Despite rapid progress, a systematic study of STFMs for ST data science remains lacking. This survey aims to provide a comprehensive review of STFMs, categorizing existing methodologies and identifying key research directions to advance ST general intelligence. Yuxuan Liang 0002, Haomin Wen, Yutong Xia, Ming Jin 0005, Bin Yang 0002, Flora D. Salim, Qingsong Wen, Shirui Pan, Gao Cong |
KDD (2) | 6 |
| 2025 | Simulated Infectious Diseases Datasets with Controlled Data BiasabstractMassive datasets related to infectious diseases became available after the COVID-19 pandemic, supporting data-driven approaches in modeling and forecasting infectious diseases. However, these approaches are known to exacerbate data biases present in the training data such as having certain demographic groups being over or underrepresented in the data. Such data collection biases may propagate through the modeling and prediction pipelines to decision-making, and the consequences are relatively unknown. Therefore, efforts are needed to understand how data collection bias affects data-driven infectious disease models. This datasets and benchmarks paper provides a suite of datasets, each corresponding to a simulated disease spread among a population of 5000 simulated agents over 90 days in Atlanta and San Francisco. For each dataset, we provide not only the full (simulated ground truth) of the disease spread in terms of when, where, and by whom the disease spreads, but also information on which cases are observed when different types and degrees of data collection bias are applied. The agents' characteristics, check-ins, and social network data are also available to support downstream tasks. Additionally, we also describe how to use the simulation to re-generate the data and to generate new datasets in different regions and with different parameters. With the provided datasets and the simulation tools, researchers studying the spread of infectious diseases may better understand, account for, and correct the systematic bias caused by the inherent real-world data bias, and hence improve the prediction of infectious diseases. Ruochen Kong 0001, Taylor Anderson 0001, Matthew Scotch, David J. Heslop, Yonchanok Khaokaew, Hao Xue 0001, Li Xiong 0001, C. Raina MacIntyre, Flora D. Salim, Andreas Züfle |
KDD (2) | 9 |
| 2025 | PAR-AdvGAN: Improving Adversarial Attack Capability with Progressive Auto-regression AdvGAN
Jiayu Zhang 0001, Xinyi Wang 0005, Silin Liao, Zhibo Jin, Flora D. Salim, Huaming Chen |
ECML/PKDD (7) | 6 |
| 2025 | MANILA25: SIGIR 2025 Workshop on Information Retrieval for Climate ImpactabstractThe MANILA25 workshop is aimed at collaborative agenda setting around the general area of information retrieval for climate impact in general and around adaptation tracking in particular. To this end, the workshop starts by creating a shared understanding of the problem space through invited talks around information needs in climate impact, search and analysis of climate impact literature, adaptation tracking, and resources. It then brings in different perspectives on the four topics through a number of brief ''flash'' presentations by participants in the workshop. Then, the participants will work to co-develop a research agenda in a small-scale, highly interactive setting. Bart van den Hurk, Maarten de Rijke, Flora D. Salim |
SIGIR | 3 |
| 2025 | How robust is your fair model? Exploring the robustness of prominent fairness strategiesabstractAbstract With the introduction of machine learning in high stakes decision-making, ensuring algorithmic fairness has become an increasingly important task. To this end, many mathematical definitions of fairness have been proposed, and a variety of optimisation techniques have been developed, all designed to maximise a given notion of fairness. Fair solutions, however, tend to rely on the quality of training data, and can be highly sensitive to noise. Recent studies have shown that robustness of many such fairness strategies—i.e., their ability to perform well on unseen data—is not a given and requires careful consideration. To address this challenge, we propose robustness ratio , which is a novel criterion to measure the robustness of diverse fairness optimisation strategies. We support our analysis with multiple extensive experiments on five benchmark fairness data sets, using three prominent fairness strategies, in view of four of the most popular definitions of fairness. Our experiments show that while fairness methods that rely on threshold optimisation (post-processing) mostly outperform other techniques, they are acutely sensitive to noise. This is in contrast to two other methods—correlation remover (pre-processing) and exponentiated gradient descent (in-processing)—which become increasingly fairer as the random noise injected into the data becomes larger. Our findings offer a comprehensive overview of fairness strategies that proves invaluable when tasked with choosing the most suitable method for the task at hand. To the best of our knowledge, we are the first to quantitatively evaluate the robustness of fairness optimisation strategies. Edward Small, Wei Shao 0006, Zeliang Zhang 0001, Peihan Liu, Jeffrey Chan, Kacper Sokol, Flora D. Salim |
Data Min. Knowl. Discov. | 7 |
| 2024 | Prompt Mining for Language Models-based Mobility Flow ForecastingabstractWith the advancement of large language models, language model-based forecasting has recently emerged as an innovative approach for predicting mobility flow patterns. The core idea is to use prompts to transform the raw mobility data given as numerical values into natural language sentences so that the language models can be leveraged to generate the description for future observations. However, previous studies have only employed fixed and manually designed templates to transform numerical values into sentences. Since the forecasting performance of language models heavily relies on prompts, using fixed templates for prompting may limit the forecasting capability of language models. In this paper, we propose a novel framework for prompt mining in language model-based mobility forecasting, aiming to explore diverse prompt design strategies. Specifically, the framework includes a prompt generation stage based on the information entropy of prompts and a prompt refinement stage to integrate mechanisms such as the chain of thought. Experimental results on real-world large-scale data demonstrate the superiority of generated prompts from our prompt mining pipeline. Additionally, the comparison of different prompt variants shows that the proposed prompt refinement process is effective. Our study presents a promising direction for further advancing language model-based mobility forecasting. Hao Xue 0001, Tianye Tang, Ali Payani, Flora D. Salim |
SIGSPATIAL/GIS | 4 |
| 2024 | T-JEPA: A Joint-Embedding Predictive Architecture for Trajectory Similarity ComputationabstractTrajectory similarity computation is crucial for analyzing movement patterns in applications like traffic management and wildlife tracking. Recent self-supervised learning methods such as contrastive learning have made advancements in trajectory representation learning but rely on predefined data augmentation schemes, limiting generalized and robust high-level semantic understanding. We introduce T-JEPA, a self-supervised method using Joint-Embedding Predictive Architecture (JEPA) to enhance trajectory representation learning. By sampling and predicting in representation space, T-JEPA infers high-level trajectory semantics without manual intervention. Extensive experiments conducted on three urban and two Foursquare datasets verify the effectiveness of T-JEPA in trajectory similarity computation. Lihuan Li, Hao Xue 0001, Yang Song 0001, Flora D. Salim |
SIGSPATIAL/GIS | 4 |
| 2024 | Enhancing Spatio-temporal Quantile Forecasting with Curriculum Learning: Lessons LearnedabstractTraining models on spatio-temporal (ST) data poses an open problem due to the complicated and diverse nature of the data itself, and it is challenging to ensure the model's performance directly trained on the original ST data. While limiting the variety of training data can make training easier, it can also lead to a lack of knowledge and information for the model, resulting in a decrease in performance. To address this challenge, we presented an innovative paradigm that incorporates three separate forms of curriculum learning specifically targeting from spatial, temporal, and quantile perspectives. Furthermore, our framework incorporates a stacking fusion module to combine diverse information from three types of curriculum learning, resulting in a strong and thorough learning process. We demonstrated the effectiveness of this framework with extensive empirical evaluations, highlighting its better performance in addressing complex ST challenges. We provided thorough ablation studies to investigate the effectiveness of our curriculum and to explain how it contributes to the improvement of learning efficiency on ST data. Du Yin, Jinliang Deng, Shuang Ao, Zechen Li 0006, Hao Xue 0001, Arian Prabowo, Renhe Jiang, Xuan Song 0001, Flora D. Salim |
SIGSPATIAL/GIS | 9 |
| 2024 | STEMO: Early Spatio-temporal Forecasting with Multi-Objective Reinforcement LearningabstractAccuracy and timeliness are indeed often conflicting goals in prediction tasks.Premature predictions may yield a higher rate of false alarms, whereas delaying predictions to gather more information can render them too late to be useful.In applications such as wildfires, crimes, and traffic jams, timely forecasting are vital for safeguarding human life and property.Consequently, finding a balance between accuracy and timeliness is crucial.In this paper, we propose an early spatio-temporal forecasting model based on Multi-Objective reinforcement learning that can either implement an optimal policy given a preference or infer the preference based on a small number of samples.The model addresses two primary challenges: 1) enhancing the accuracy of early forecasting and 2) providing the optimal policy for determining the most suitable prediction time for each area.Our method demonstrates superior performance on three large-scale real-world datasets, surpassing existing methods in early spatio-temporal forecasting tasks. Wei Shao 0006, Yufan Kang, Ziyan Peng, Xiao Xiao 0007, Lei Wang 0266, Yuhui Yang, Flora D. Salim |
KDD | 7 |
| 2024 | Long-Term Fairness in Ride-Hailing Platform
Yufan Kang, Jeffrey Chan, Wei Shao 0006, Flora D. Salim, Christopher Leckie |
ECML/PKDD (9) | 4 |
| 2024 | Boosting Patient Representation Learning via Graph Contrastive Learning
Yuxi Liu 0003, Jiang Bian 0001, Antonio Jimeno-Yepes, Jun Shen 0001, Fuyi Li, Guodong Long, Flora D. Salim |
ECML/PKDD (9) | 8 |
| 2024 | CAPRI-FAIR: Integration of Multi-sided Fairness in Contextual POI Recommendation FrameworkabstractPoint-of-interest (POI) recommendation considers spatio-temporal factors like distance, peak hours, and user check-ins. Given their influence on both consumer experience and POI business, it’s crucial to consider fairness from multiple perspectives. Unfortunately, these systems often provide less accurate recommendations to inactive users and less exposure to unpopular POIs. This paper develops a post-filter method that includes provider and consumer fairness in existing models, aiming to balance fairness metrics like item exposure with performance metrics such as precision and distance. Experiments show that a linear scoring model for provider fairness in re-scoring items offers the best balance between performance and long-tail exposure, sometimes without much precision loss. Addressing consumer fairness by recommending more popular POIs to inactive users increased precision in some models and datasets. However, combinations that reached the Pareto front of consumer and provider fairness resulted in the lowest precision values, highlighting that tradeoffs depend greatly on the model and dataset. Francis Zac dela Cruz, Flora D. Salim, Yonchanok Khaokaew, Jeffrey Chan |
RecSys | 2 |
| 2024 | MANILA24: SIGIR 2024 Workshop on Information Retrieval and Climate ImpactabstractThe MANILA24 workshop brings together researchers and practitioners from academia, industry, governments, and NGO's to identify and discuss core research problems in information retrieval for climate impact. The workshop aims to foster collaboration by bringing communities together that have so far not been very well connected -- IR, systematic reviews, and climate change. The purpose is to help accelerate the development of IR technology that supports our understanding of climate impact publications and the articulation of recommended actions. Importantly, this includes introducing IR researchers climate impact, introducing researchers in climate to state-of-the-art IR technology, and developing a shared research agenda. Bart van den Hurk, Maarten de Rijke, Flora D. Salim |
SIGIR | 3 |
| 2024 | Characterizing Information Seeking Processes with Multiple Physiological SignalsabstractInformation access systems are getting complex, and our understanding of user behavior during information seeking processes is mainly drawn from qualitative methods, such as observational studies or surveys. Leveraging the advances in sensing technologies, our study aims to characterize user behaviors with physiological signals, particularly in relation to cognitive load, affective arousal, and valence. We conduct a controlled lab study with 26 participants, and collect data including Electrodermal Activities, Photoplethysmogram, Electroencephalogram, and Pupillary Responses. This study examines informational search with four stages: the realization of Information Need (IN), Query Formulation (QF), Query Submission (QS), and Relevance Judgment (RJ). We also include different interaction modalities to represent modern systems, e.g., QS by text-typing or verbalizing, and RJ with text or audio information. We analyze the physiological signals across these stages and report outcomes of pairwise non-parametric repeated-measure statistical tests. The results show that participants experience significantly higher cognitive loads at IN with a subtle increase in alertness, while QF requires higher attention. QS involves demanding cognitive loads than QF. Affective responses are more pronounced at RJ than QS or IN, suggesting greater interest and engagement as knowledge gaps are resolved. To the best of our knowledge, this is the first study that explores user behaviors in a search process employing a more nuanced quantitative analysis of physiological signals. Our findings offer valuable insights into user behavior and emotional responses in information seeking processes. We believe our proposed methodology can inform the characterization of more complex processes, such as conversational information seeking. Kaixin Ji, Danula Hettiachchi, Flora D. Salim, Falk Scholer, Damiano Spina |
SIGIR | 3 |
| 2024 | Large Language Models for Next Point-of-Interest RecommendationabstractThe next Point of Interest (POI) recommendation task is to predict users' immediate next POI visit given their historical data. Location-Based Social Network (LBSN) data, which is often used for the next POI recommendation task, comes with challenges. One frequently disregarded challenge is how to effectively use the abundant contextual information present in LBSN data. Previous methods are limited by their numerical nature and fail to address this challenge. In this paper, we propose a framework that uses pretrained Large Language Models (LLMs) to tackle this challenge. Our framework allows us to preserve heterogeneous LBSN data in its original format, hence avoiding the loss of contextual information. Furthermore, our framework is capable of comprehending the inherent meaning of contextual information due to the inclusion of commonsense knowledge. In experiments, we test our framework on three real-world LBSN datasets. Our results show that the proposed framework outperforms the state-of-the-art models in all three datasets. Our analysis demonstrates the effectiveness of the proposed framework in using contextual information as well as alleviating the commonly encountered cold-start and short trajectory problems. Peibo Li 0001, Maarten de Rijke, Hao Xue 0001, Shuang Ao, Yang Song 0001, Flora D. Salim |
SIGIR | 6 |
| 2024 | CroSSL: Cross-modal Self-Supervised Learning for Time-series through Latent MaskingabstractLimited availability of labeled data for machine learning on multimodal time-series extensively hampers progress in the field. Self-supervised learning (SSL) is a promising approach to learn data representations without relying on labels. However, existing SSL methods require expensive computations of negative pairs and are typically designed for single modalities, which limits their versatility. We introduce CroSSL (Cross-modal SSL), which puts forward two novel concepts: masking intermediate embeddings produced by modality-specific encoders, and their aggregation into a global embedding through a cross-modal aggregator CroSSL allows for handling missing modalities and end-to-end cross-modal earning without requiring prior data preprocessing for handling missing inputs or negative-pair sampling for contrastive learning. We evaluate our method on a wide range of data, including motion sensors such as accelerometers or gyroscopes and biosignals (heart rate, electroencephalograms, electromyograms, electrooculograms, and electrodermal). Overall, CroSSL outperforms previous SSL and supervised benchmarks using minimal labeled data, and also sheds light on how latent masking can improve cross-modal learning. Shohreh Deldari, Dimitris Spathis, Mohammad Malekzadeh, Fahim Kawsar, Flora D. Salim, Akhil Mathur |
WSDM | 5 |
| 2024 | SSTKG: Simple Spatio-Temporal Knowledge Graph for Intepretable and Versatile Dynamic Information EmbeddingabstractKnowledge graphs (KGs) have been increasingly employed for link prediction and recommendation using real-world datasets. However, the majority of current methods rely on static data, neglecting the dynamic nature and the hidden spatio-temporal attributes of real-world scenarios. This often results in suboptimal predictions and recommendations. Although there are effective spatio-temporal inference methods, they face challenges such as scalability with large datasets and inadequate semantic understanding, which impede their performance. To address these limitations, this paper introduces a novel framework - Simple Spatio-Temporal Knowledge Graph (SSTKG), for constructing and exploring spatio-temporal KGs. To integrate spatial and temporal data into KGs, our framework exploited through a new 3-step embedding method. Output embeddings can be used for future temporal sequence prediction and spatial information recommendation, providing valuable insights for various applications such as retail sales forecasting and traffic volume prediction. Our framework offers a simple but comprehensive way to understand the underlying patterns and trends in dynamic KG, thereby enhancing the accuracy of predictions and the relevance of recommendations. This work paves the way for more effective utilization of spatio-temporal data in KGs, with potential impacts across a wide range of sectors. Flora D. Salim, Hao Xue 0001 |
WWW | 2 |
| 2024 | Traffic forecasting on new roads using spatial contrastive pre-training (SCPT)abstractAbstract New roads are being constructed all the time. However, the capabilities of previous deep forecasting models to generalize to new roads not seen in the training data (unseen roads) are rarely explored. In this paper, we introduce a novel setup called a spatio-temporal split to evaluate the models’ capabilities to generalize to unseen roads. In this setup, the models are trained on data from a sample of roads, but tested on roads not seen in the training data. Moreover, we also present a novel framework called Spatial Contrastive Pre-Training (SCPT) where we introduce a spatial encoder module to extract latent features from unseen roads during inference time. This spatial encoder is pre-trained using contrastive learning. During inference, the spatial encoder only requires two days of traffic data on the new roads and does not require any re-training. We also show that the output from the spatial encoder can be used effectively to infer latent node embeddings on unseen roads during inference time. The SCPT framework also incorporates a new layer, named the spatially gated addition layer, to effectively combine the latent features from the output of the spatial encoder to existing backbones. Additionally, since there is limited data on the unseen roads, we argue that it is better to decouple traffic signals to trivial-to-capture periodic signals and difficult-to-capture Markovian signals, and for the spatial encoder to only learn the Markovian signals. Finally, we empirically evaluated SCPT using the ST split setup on four real-world datasets. The results showed that adding SCPT to a backbone consistently improves forecasting performance on unseen roads. More importantly, the improvements are greater when forecasting further into the future. The codes are available on GitHub: https://github.com/cruiseresearchgroup/forecasting-on-new-roads . Arian Prabowo, Hao Xue 0001, Wei Shao 0006, Piotr Koniusz, Flora D. Salim |
Data Min. Knowl. Discov. | 5 |
| 2024 | PromptCast: A New Prompt-Based Learning Paradigm for Time Series ForecastingabstractThis paper presents a new perspective on time series forecasting. In existing time series forecasting methods, the models take a sequence of numerical values as input and yield numerical values as output. The existing SOTA models are largely based on the Transformer architecture, modified with multiple encoding mechanisms to incorporate the context and semantics around the historical data. Inspired by the successes of pre-trained language foundation models, we pose a question about whether these models can also be adapted to solve time-series forecasting. Thus, we propose a new forecasting paradigm: prompt-based time series forecasting (PromptCast). In this novel task, the numerical input and output are transformed into prompts and the forecasting task is framed in a sentence-to-sentence manner, making it possible to directly apply language models for forecasting purposes. To support and facilitate the research of this task, we also present a large-scale dataset (PISA) that includes three real-world forecasting scenarios. We evaluate different SOTA numerical-based forecasting methods and language generation models. The benchmark results with various forecasting settings demonstrate the proposed PromptCast with language generation models is a promising research direction. Additionally, in comparison to conventional numerical-based forecasting, PromptCast shows a much better generalization ability under the zero-shot setting. Hao Xue 0001, Flora D. Salim |
IEEE Trans. Knowl. Data Eng. | 2 |
| 2023 | Designing and Evaluating Presentation Strategies for Fact-Checked ContentabstractWith the rapid growth of online misinformation, it is crucial to have reliable fact-checking methods. Recent research on finding check-worthy claims and automated fact-checking have made significant advancements. However, limited guidance exists regarding the presentation of fact-checked content to effectively convey verified information to users. We address this research gap by exploring the critical design elements in fact-checking reports and investigating whether credibility and presentation-based design improvements can enhance users' ability to interpret the report accurately. We co-developed potential content presentation strategies through a workshop involving fact-checking professionals, communication experts, and researchers. The workshop examined the significance and utility of elements such as veracity indicators and explored the feasibility of incorporating interactive components for enhanced information disclosure. Building on the workshop outcomes, we conducted an online experiment involving 76 crowd workers to assess the efficacy of different design strategies. The results indicate that proposed strategies significantly improve users' ability to accurately interpret the verdict of fact-checking articles. Our findings underscore the critical role of effective presentation of fact reports in addressing the spread of misinformation. By adopting appropriate design enhancements, the effectiveness of fact-checking reports can be maximized, enabling users to make informed judgments. Danula Hettiachchi, Kaixin Ji, Jenny Kennedy, Anthony McCosker, Flora D. Salim, Mark Sanderson, Falk Scholer, Damiano Spina |
CIKM | 5 |
| 2023 | Artificial General Intelligence for Human Mobility (Vision Paper)abstractThis paper presents a visionary perspective on developing Artificial General Intelligence (AGI) in the field of human mobility research. Human mobility profoundly influences our daily lives, impacting transportation systems, urban planning, logistics, and healthcare. While AI methods have made significant advancements in addressing human mobility challenges, they often struggle with the complexity and dynamic nature of this domain. The limitations arise from the narrow focus of existing AI systems, lacking the ability to generalize and adapt to new situations. To overcome these limitations, there is a growing interest in developing AGI systems. This paper explores the potential of AGI to revolutionize human mobility research by enabling systems to understand, learn, reason, and adapt across diverse domains and tasks. To achieve this goal, we propose the Mobility Foundation Model (MFM) and the concept of an intermediate modality is further introduced as a means to bridge the gap between different mobility modalities and scales. The unified representation allows the MFM to effectively learn and integrate information from various modalities. We also present a novel MFM as Administrator paradigm for leveraging MFM in complex mobility tasks. We hope that this paper will provide novel insights and open new directions in human mobility research. Hao Xue 0001, Flora D. Salim |
SIGSPATIAL/GIS | 2 |
| 2023 | Are footpaths encroached by shared e-scooters? Spatio-temporal Analysis of Micro-mobility ServicesabstractMicro-mobility services (e.g., e-bikes, e-scooters) are increasingly popular among urban communities, being a flexible transport option that brings both opportunities and challenges. As a growing mode of transportation, insights gained from micro-mobility usage data are valuable in policy formulation and improving the quality of services. Existing research analyses patterns and features associated with usage distributions in different localities, and focuses on either temporal or spatial aspects. In this paper, we employ a combination of methods that analyse both spatial and temporal characteristics related to e-scooter trips in a more granular level, enabling observations at different time frames and local geographical zones that prior analysis wasn’t able to do. The insights obtained from anonymised, restricted data on shared e-scooter rides show the applicability of the employed method on regulated, privacy preserving micro-mobility trip data. Our results showed population density is the topmost important feature, and it associates with e-scooter usage positively. Population owning motor vehicles is negatively associated with shared e-scooter trips, suggesting a reduction in e-scooter usage among motor vehicle owners. Furthermore, we found that the effect of humidity is more important than precipitation in predicting hourly e-scooter trip count. Buffer analysis showed, nearly 29% trips were stopped, and 27% trips were started on the footpath, revealing higher utilisation of footpaths for parking e-scooters in Melbourne. Hiruni Kegalle, Danula Hettiachchi, Jeffrey Chan, Flora D. Salim, Mark Sanderson |
MDM | 4 |
| 2023 | Self-supervised Activity Representation Learning with Incremental Data: An Empirical StudyabstractIn the context of mobile sensing environments, various sensors on mobile devices continually generate a vast amount of data. Analyzing this ever-increasing data presents several challenges, including limited access to annotated data and a constantly changing environment. Recent advancements in self-supervised learning have been utilized as a pre-training step to enhance the performance of conventional supervised models to address the absence of labelled datasets. This research examines the impact of using a self-supervised representation learning model for time series classification tasks in which data is incrementally available. We proposed and evaluated a workflow in which a model learns to extract informative features using a corpus of unlabeled time series data and then conducts classification on labelled data using features extracted by the model. We analyzed the effect of varying the size, distribution, and source of the unlabeled data on the final classification performance across four public datasets, including various types of sensors in diverse applications. Shohreh Deldari, Hao Xue 0001, Flora D. Salim |
MDM | 5 |
| 2023 | A System of Monitoring and Analyzing Human Indoor Mobility and Air QualityabstractHuman movements in the workspace usually have non-negligible relations with air quality parameters (e.g., CO2, PM2.5, and PM10). We establish a system to monitor indoor human mobility with air quality and assess the interrelationship between these two types of time series data. More specifically, a sensor network was designed in indoor environments to observe air quality parameters continuously. Simultaneously, another sensing module detected participants’ movements around the study areas. In this module, modern data analysis and machine learning techniques have been applied to reconstruct the trajectories of participants with relevant sensor information. Finally, a further study revealed the correlation between human indoor mobility patterns and indoor air quality parameters. Our experimental results demonstrate that human movements in different environments can significantly impact air quality during busy hours. With the results, we propose recommendations for future studies. Kyle Kai Qin, Mohammad Saiedur Rahaman, Yongli Ren, Chi-Tsun Cheng, Ivan Cole, Flora D. Salim |
MDM | 6 |
| 2023 | Examining the Impact of Uncontrolled Variables on Physiological Signals in User Studies for Information Processing ActivitiesabstractPhysiological signals can potentially be applied as objective measures to understand the behavior and engagement of users interacting with information access systems. However, the signals are highly sensitive, and many controls are required in laboratory user studies. To investigate the extent to which controlled or uncontrolled (i.e., confounding) variables such as task sequence or duration influence the observed signals, we conducted a pilot study where each participant completed four types of information-processing activities (READ, LISTEN, SPEAK, and WRITE). Meanwhile, we collected data on blood volume pulse, electrodermal activity, and pupil responses. We then used machine learning approaches as a mechanism to examine the influence of controlled and uncontrolled variables that commonly arise in user studies. Task duration was found to have a substantial effect on the model performance, suggesting it represents individual differences rather than giving insight into the target variables. This work contributes to our understanding of such variables in using physiological signals in information retrieval user studies. Kaixin Ji, Damiano Spina, Danula Hettiachchi, Flora D. Salim, Falk Scholer |
SIGIR | 4 |
| 2023 | i-Align: an interpretable knowledge graph alignment modelabstractAbstract Knowledge graphs (KGs) are becoming essential resources for many downstream applications. However, their incompleteness may limit their potential. Thus, continuous curation is needed to mitigate this problem. One of the strategies to address this problem is KG alignment, i.e., forming a more complete KG by merging two or more KGs. This paper proposes i-Align, an interpretable KG alignment model. Unlike the existing KG alignment models, i-Align provides an explanation for each alignment prediction while maintaining high alignment performance. Experts can use the explanation to check the correctness of the alignment prediction. Thus, the high quality of a KG can be maintained during the curation process (e.g., the merging process of two KGs). To this end, a novel Transformer-based Graph Encoder (Trans-GE) is proposed as a key component of i-Align for aggregating information from entities’ neighbors (structures). Trans-GE uses Edge-gated Attention that combines the adjacency matrix and the self-attention matrix to learn a gating mechanism to control the information aggregation from the neighboring entities. It also uses historical embeddings, allowing Trans-GE to be trained over mini-batches, or smaller sub-graphs, to address the scalability issue when encoding a large KG. Another component of i-Align is a Transformer encoder for aggregating entities’ attributes. This way, i-Align can generate explanations in the form of a set of the most influential attributes/neighbors based on attention weights. Extensive experiments are conducted to show the power of i-Align. The experiments include several aspects, such as the model’s effectiveness for aligning KGs, the quality of the generated explanations, and its practicality for aligning large KGs. The results show the effectiveness of i-Align in these aspects. Bayu Distiawan Trisedya, Flora D. Salim, Jeffrey Chan, Damiano Spina, Falk Scholer, Mark Sanderson |
Data Min. Knowl. Discov. | 2 |
| 2023 | Qualitative spatial reasoning with uncertain evidence using Markov logic networksabstractProbabilistic logics combine the ability to reason about complex scenes, with a rigorous approach to uncertainty. This paper explores the construction of probabilistic spatial logics through the combination of established qualitative spatial calculi together with Markov logic networks (MLNs). Qualitative spatial calculi provide the basis for automated representation and reasoning with complex spatial scenes; MLNs provide a rigorous basis for handling uncertainty and driving probabilistic inference. Our approach focuses specifically on the combination of an uncertain knowledge base with a certain spatial reasoning rule-base. The experiments explore how uncertain knowledge propagates through certain qualitative spatial inferences, using the specific example of reasoning with cardinal directions. The results provide a template for probabilistic qualitative spatial reasoning more generally, with applications to a wide range of common scenarios for situational awareness and automated reasoning under uncertainty. Matt Duckham, Jelena Gabela, Allison Kealy, Ross Kyprianou, Jonathan Legg, William Moran 0001, Shakila Khan Rumi, Flora D. Salim, Yaguang Tao, Maria Vasardani |
Int. J. Geogr. Inf. Sci. | 8 |
| 2023 | TransCP: A Transformer Pointer Network for Generic Entity Description Generation With Explicit Content-PlanningabstractWe study neural data-to-text generation to generate a sentence to describe a target entity based on its attributes. Specifically, we address two problems of the encoder-decoder framework for data-to-text generation: i) how to encode a non-linear input (e.g., a set of attributes); and ii) how to order the attributes in the generated description. Existing studies focus on the encoding problem but do not address the ordering problem, i.e., they learn the content-planning implicitly. The other approaches focus on two-stage models but overlook the encoding problem. To address the two problems at once, we propose a model namedTransCPto explicitly learn content-planning and integrate them into a description generation model in an end-to-end fashion. We propose a novel Transformer-based Pointer Network withgated residual attentionandimportance maskingto learn a content-plan. To integrate the content-plan with a description generator, we propose a tracking mechanism to trace the extent to which the content-plan is exposed in the previous decoding time-step. This helps the description generator select the attributes to be mentioned in proper order. Experimental results show that our model consistently outperforms state-of-the-art baselines by up to 2% and 3% in terms of BLEU score on two real-world datasets. Bayu Distiawan Trisedya, Jianzhong Qi 0001, Hai-Tao Zheng 0002, Flora D. Salim, Rui Zhang 0003 |
IEEE Trans. Knowl. Data Eng. | 4 |
| 2022 | Leveraging language foundation models for human mobility forecastingabstractIn this paper, we propose a novel pipeline that leverages language foundation models for temporal sequential pattern mining, such as for human mobility forecasting tasks. For example, in the task of predicting Place-of-Interest (POI) customer flows, typically the number of visits is extracted from historical logs, and only the numerical data are used to predict visitor flows. In this research, we perform the forecasting task directly on the natural language input that includes all kinds of information such as numerical values and contextual semantic information. Specific prompts are introduced to transform numerical temporal sequences into sentences so that existing language models can be directly applied. We design an AuxMobLCast pipeline for predicting the number of visitors in each POI, integrating an auxiliary POI category classification task with the encoder-decoder architecture. This research provides empirical evidence of the effectiveness of the proposed AuxMobLCast pipeline to discover sequential patterns in mobility forecasting tasks. The results, evaluated on three real-world datasets, demonstrate that pre-trained language foundation models also have good performance in forecasting temporal sequences. This study could provide visionary insights and lead to new research directions for predicting human mobility. Hao Xue 0001, Bhanu Prakash Voutharoja, Flora D. Salim |
SIGSPATIAL/GIS | 3 |
| 2022 | Measuring disentangled generative spatio-temporal representationabstractDisentangled representation learning offers useful properties such as dimension reduction and interpretability, which are essential to modern deep learning approaches. Although deep learning techniques have been widely applied to spatio-temporal data mining, there has been little attention to further disentangle the latent features and understanding their contribution to the model performance, particularly their mutual information and correlation across features. In this study, we adopt two state-of-the-art disentangled representation learning methods and apply them to three large-scale public spatio-temporal datasets. To evaluate their performance, we propose an internal evaluation metric focusing on the degree of correlations among latent variables of the learned representations and the prediction performance of the downstream tasks. Empirical results show that our modified method can learn disentangled representations that achieve the same level of performance as existing state-of-the-art ST deep learning methods in a spatio-temporal sequence forecasting problem. Additionally, we find that our methods can be used to discover real-world spatial-temporal semantics to describe the variables in the learned representation. Sichen Zhao, Wei Shao 0006, Jeffrey Chan, Flora D. Salim |
SDM | 4 |
| 2022 | Translating Human Mobility Forecasting through Natural Language GenerationabstractExisting human mobility forecasting models follow the standard design of the time-series prediction model which takes a series of numerical values as input to generate a numerical value as a prediction. Although treating this as a regression problem seems straightforward, incorporating various contextual information such as the semantic category information of each Place-of-Interest (POI) is a necessary step, and often the bottleneck, in designing an effective mobility prediction model. As opposed to the typical approach, we treat forecasting as a translation problem and propose a novel forecasting through a language generation pipeline. The paper aims to address the human mobility forecasting problem as a language translation task in a sequence-to-sequence manner. A mobility-to-language template is first introduced to describe the numerical mobility data as natural language sentences. The core intuition of the human mobility forecasting translation task is to convert the input mobility description sentences into a future mobility description from which the prediction target can be obtained. Under this pipeline, a two-branch network, SHIFT (Translating Human Mobility Forecasting), is designed. Specifically, it consists of one main branch for language generation and one auxiliary branch to directly learn mobility patterns. During the training, we develop a momentum mode for better connecting and training the two branches. Extensive experiments on three real-world datasets demonstrate that the proposed SHIFT is effective and presents a new revolutionary approach to forecasting human mobility. Hao Xue 0001, Flora D. Salim, Yongli Ren, Charles L. A. Clarke |
WSDM | 2 |
| 2022 | Generative Adversarial Networks for Spatio-temporal Data: A SurveyabstractGenerative Adversarial Networks (GANs) have shown remarkable success in producing realistic-looking images in the computer vision area. Recently, GAN-based techniques are shown to be promising for spatio-temporal-based applications such as trajectory prediction, events generation, and time-series data imputation. While several reviews for GANs in computer vision have been presented, no one has considered addressing the practical applications and challenges relevant to spatio-temporal data. In this article, we have conducted a comprehensive review of the recent developments of GANs for spatio-temporal data. We summarise the application of popular GAN architectures for spatio-temporal data and the common practices for evaluating the performance of spatio-temporal applications with GANs. Finally, we point out future research directions to benefit researchers in this area. Nan Gao 0001, Hao Xue 0001, Wei Shao 0006, Sichen Zhao, Kyle Kai Qin, Arian Prabowo, Mohammad Saiedur Rahaman, Flora D. Salim |
ACM Trans. Intell. Syst. Technol. | 8 |
| 2021 | CoSEM: Contextual and Semantic Embedding for App Usage PredictionabstractApp usage prediction is important for smartphone system optimization to enhance user experience. Existing modeling approaches utilize historical app usage logs along with a wide range of semantic information to predict the app usage; however, they are only effective in certain scenarios and cannot be generalized across different situations. This paper address this problem by developing a model called Contextual and Semantic Embedding model for App Usage Prediction (CoSEM) for app usage prediction that leverages integration of 1) semantic information embedding and 2) contextual information embedding based on historical app usage of individuals. Extensive experiments show that the combination of semantic information and history app usage information enables our model to outperform the baselines on three real-world datasets, achieving an MRR score over 0.55,0.57,0.86 and Hit rate scores of more than 0.71, 0.75, and 0.95, respectively. Yonchanok Khaokaew, Mohammad Saiedur Rahaman, Ryen W. White, Flora D. Salim |
CIKM | 4 |
| 2021 | PIETS: Parallelised Irregularity Encoders for Forecasting with Heterogeneous Time-SeriesabstractHeterogeneity and irregularity of multi-source data sets present a significant challenge to time-series analysis. In the literature, the fusion of multi-source time-series has been achieved either by using ensemble learning models which ignore temporal patterns and correlation within features or by defining a fixed-size window to select specific parts of the data sets. On the other hand, many studies have shown major improvement to handle the irregularity of time-series, yet none of these studies has been applied to multi-source data. In this work, we design a novel architecture, PIETS, to model heterogeneous time-series. PIETS has the following characteristics: (1) irregularity encoders for multi-source samples that can leverage all available information and accelerate the convergence of the model; (2) parallelised neural networks to enable flexibility and avoid information overwhelming; and (3) attention mechanism that highlights different information and gives high importance to the most related data. Through extensive experiments on real-world data sets related to COVID-19, we show that the proposed architecture is able to effectively model heterogeneous temporal data and outperforms other state-of-the-art approaches in the prediction task. Futoon M. Abushaqra, Hao Xue 0001, Yongli Ren, Flora D. Salim |
ICDM | 4 |
| 2021 | Exploring Self-Supervised Representation Ensembles for COVID-19 Cough ClassificationabstractThe usage of smartphone-collected respiratory sound, trained with deep learning models, for detecting and classifying COVID-19 becomes popular recently. It removes the need for in-person testing procedures especially for rural regions where related medical supplies, experienced workers, and equipment are limited. However, existing sound-based diagnostic approaches are trained in a fully-supervised manner, which requires large scale well-labelled data. It is critical to discover new methods to leverage unlabelled respiratory data, which can be obtained more easily. In this paper, we propose a novel self-supervised learning enabled framework for COVID-19 cough classification. A contrastive pre-training phase is introduced to train a Transformer-based feature encoder with unlabelled data. Specifically, we design a random masking mechanism to learn robust representations of respiratory sounds. The pre-trained feature encoder is then fine-tuned in the downstream phase to perform cough classification. In addition, different ensembles with varied random masking rates are also explored in the downstream phase. Through extensive evaluations, we demonstrate that the proposed contrastive pre-training, the random masking mechanism, and the ensemble architecture contribute to improving cough classification performance. Hao Xue 0001, Flora D. Salim |
KDD | 2 |
| 2021 | TERMCast: Temporal Relation Modeling for Effective Urban Flow Forecasting
Hao Xue 0001, Flora D. Salim |
PAKDD (1) | 2 |
| 2021 | MoParkeR : Multi-objective Parking RecommendationabstractExisting parking recommendation solutions mainly focus on finding and suggesting parking spaces based on the unoccupied options only. However, there are other factors associated with parking spaces that can influence someone’s choice of parking such as fare, parking rule, walking distance to destination, travel time, likelihood to be unoccupied at a given time. More importantly, these factors may change over time and conflict with each other which makes the recommendations produced by current parking recommender systems ineffective. In this paper, we propose a novel problem called multi-objective parking recommendation. We present a solution by designing a multi-objective parking recommendation engine called MoParkeR that considers various conflicting factors together. Specifically, we utilise a non-dominated sorting technique to calculate a set of Pareto-optimal solutions, consisting of recommended trade-off parking spots. We conduct extensive experiments using two real-world datasets to show the applicability of our multi-objective recommendation methodology. Mohammad Saiedur Rahaman, Wei Shao 0006, Flora D. Salim, Ayad Mashaan Turky, Andy Song, Jeffrey Chan, Junliang Jiang, Doug Bradbrook |
SSDBM | 3 |
| 2021 | Time Series Change Point Detection with Self-Supervised Contrastive Predictive CodingabstractChange Point Detection (CPD) methods identify the times associated with changes in the trends and properties of time series data in order to describe the underlying behaviour of the system. For instance, detecting the changes and anomalies associated with web service usage, application usage or human behaviour can provide valuable insights for downstream modelling tasks. We propose a novel approach for self-supervised Time Series Change Point detection method based on Contrastive Predictive coding (TS − CP2). TS − CP2 is the first approach to employ a contrastive learning strategy for CPD by learning an embedded representation that separates pairs of embeddings of time adjacent intervals from pairs of interval embeddings separated across time. Through extensive experiments on three diverse, widely used time series datasets, we demonstrate that our method outperforms five state-of-the-art CPD methods, which include unsupervised and semi-supervised approaches. TS − CP2 is shown to improve the performance of methods that use either handcrafted statistical or temporal features by 79.4% and deep learning-based methods by 17.0% with respect to the F1-score averaged across the three datasets. Shohreh Deldari, Daniel V. Smith, Hao Xue 0001, Flora D. Salim |
WWW | 4 |
| 2020 | G-CREWE: Graph CompREssion With Embedding for Network AlignmentabstractNetwork alignment is useful for multiple applications that require increasingly large graphs to be processed. Existing research approaches this as an optimization problem or computes the similarity based on node representations. However, the process of aligning every pair of nodes between relatively large networks is time-consuming and resource-intensive. In this paper, we propose a framework, called G-CREWE (Graph CompREssion With Embedding) to solve the network alignment problem. G-CREWE uses node embeddings to align the networks on two levels of resolution, a fine resolution given by the original network and a coarse resolution given by a compressed version, to achieve an efficient and effective network alignment. The framework first extracts node features and learns the node embedding via a Graph Convolutional Network (GCN). Then, node embedding helps to guide the process of graph compression and finally improve the alignment performance. As part of G-CREWE, we also propose a new compression mechanism called MERGE (Minimum DEgRee NeiGhbors ComprEssion) to reduce the size of the input networks while preserving the consistency in their topological structure. Experiments on all real networks show that our method is more than twice as fast as the most competitive existing methods while maintaining high accuracy. Kyle Kai Qin, Flora D. Salim, Yongli Ren, Wei Shao 0006, Mark Heimann, Danai Koutra |
CIKM | 2 |
| 2020 | Modelling Regional Crime Risk using Directed Graph of Check-insabstractThe location-based social network, Foursquare, reflects the human activities of a city. The mobility dynamics inferred from Foursquare helps us understanding urban social events like crime In this paper, we propose a directed graph from the aggregated movement between regions using Foursquare data. We derive region risk factor from the movement direction, quantity and crime history in different periods of the day. Later, we propose a new set of features, DIrected graph Flow FEatuRes (DIFFER) which are associated with region risk factor. The reliable correlations between DIFFER and crime count are observed. We verify the effectiveness of the DIFFER in monthly crime count using Linear, XGBoost, and Random Forest regression in two cities, Chicago and New York City. Shakila Khan Rumi, Flora D. Salim |
CIKM | 2 |
| 2020 | Realtime Predictive Patrolling and Routing with Mobility and Emergency Calls Data
Shakila Khan Rumi, Wei Shao 0006, Flora D. Salim |
ICWSM | 3 |
| 2020 | Intelligent Task Recognition: Towards Enabling Productivity Assistance in Daily LifeabstractWe introduce the novel research problem of task recognition in daily life. We recognize tasks such as project management, planning, meal-breaks, communication, documentation, and family care. We capture Cyber, Physical, and Social (CPS) activities of 17 participants over four weeks using device-based sensing, app activity logging, and an experience sampling methodology. Our cohort includes students, casual workers, and professionals, forming the first real-world context-rich task behaviour dataset. We model CPS activities across different task categories, results highlight the importance of considering the CPS feature sets in modelling, especially work-related tasks. Jonathan Liono, Mohammad Saiedur Rahaman, Flora D. Salim, Yongli Ren, Damiano Spina, Falk Scholer, Johanne R. Trippas, Mark Sanderson, Paul N. Bennett, Ryen W. White |
ICMR | 3 |
| 2020 | Relation Embedding for Personalised Translation-Based POI Recommendation
Xianjing Wang, Flora D. Salim, Yongli Ren, Piotr Koniusz |
PAKDD (1) | 2 |
| 2020 | Unsupervised online change point detection in high-dimensional time series
Masoomeh Zameni, Amin Sadri, Zahra Ghafoori, Masud Moshtaghi, Flora D. Salim, Christopher Leckie, Kotagiri Ramamohanarao |
Knowl. Inf. Syst. | 5 |
| 2019 | Learning About Work Tasks to Inform Intelligent Assistant DesignabstractIntelligent assistants can serve many purposes, including entertainment (e.g. playing music), home automation, and task management (e.g. timers, reminders). The role of these assistants is evolving to also support people engaged in work tasks, in workplaces and beyond. To design truly useful intelligent assistants for work, it is important to better understand the work tasks that people are performing. Based on a survey of 401 respondents' daily tasks and activities in a work setting, we present a classification of work-related tasks, and analyze their key characteristics, including the frequency of their self-reported tasks, the environment in which they undertake the tasks, and which, if any, electronic devices are used. We also investigate the cyber, physical, and social aspects of tasks. Finally, we reflect on how intelligent assistants could influence and help people in a work environment to complete their tasks, and synthesize our findings to provide insight on the future of intelligent assistants in support of amplifying personal productivity. Johanne R. Trippas, Damiano Spina, Falk Scholer, Ahmed Awadallah 0001, Peter Bailey, Paul N. Bennett, Ryen W. White, Jonathan Liono, Yongli Ren, Flora D. Salim, Mark Sanderson |
CHIIR | 10 |
| 2019 | Flight Delay Prediction using Airport Situational Awareness MapabstractThe prediction of flight delays plays a significantly important role for airlines and travellers because flight delays cause not only tremendous economic loss but also potential security risks. In this work, we aim to integrate multiple data sources to predict the departure delay of a scheduled flight. Different from previous work, we are the first group, to our best knowledge, to take advantage of airport situational awareness map, which is defined as airport traffic complexity (ATC), and combine the proposed ATC factors with weather conditions and light information. Features engineering methods and most state-of-the-art machine learning algorithms are applied to a large real-world data sources. We reveal a couple of factors at the airport which has a significant impact on flight departure delay time. The prediction results show that the proposed factors are the main reasons behind the flight delays. Using our proposed framework, an improvement in accuracy for flight departure delay prediction is obtained. Wei Shao 0006, Arian Prabowo, Sichen Zhao, Siyu Tan, Piotr Koniusz, Jeffrey Chan, Xinhong Hei 0001, Bradley Feest, Flora D. Salim |
SIGSPATIAL/GIS | 9 |
| 2019 | Efficient trip scheduling algorithms for groups
Roksana Jahan, Tanzima Hashem, Flora D. Salim, Sukarna Barua |
Inf. Syst. | 3 |
| 2018 | Theft prediction with individual risk factor of visitorsabstractLocation-Based Social Networks (LBSN) provides unprecedented opportunities to tackle various social problems. In this study, we identify a number of crime-prediction-specific dynamic features which, for the first time, explore crime risk factors implicitly associated with the visitors. The reliable correlations between the proposed dynamic features and crime event occurrences have been observed. The evaluations on large real world data sets verify that the crime prediction performance can be notably improved with the inclusion of proposed crime-prediction-specific dynamic features. Shakila Khan Rumi, Flora D. Salim |
SIGSPATIAL/GIS | 3 |
| 2018 | Identifying In-App User Actions from Mobile Web Logs
Bilih Priyogi, Mark Sanderson, Flora D. Salim, Jeffrey Chan, Martin Tomko 0001, Yongli Ren |
PAKDD (2) | 3 |
| 2018 | Mining User Behavioral Rules from Smartphone Data Through Association Analysis
Iqbal H. Sarker, Flora D. Salim |
PAKDD (1) | 2 |
| 2018 | A Location-Query-Browse Graph for Contextual RecommendationabstractTraditionally, recommender systems modelled the physical and cyber contextual influence on people's moving, querying, and browsing behaviors in isolation. Yet, searching, querying, and moving behaviors are intricately linked, especially indoors. Here, we introduce a tripartite location-query-browse graph (LQB) for nuanced contextual recommendations. The LQB graph consists of three kinds of nodes: locations, queries, and Web domains. Directed connections only between heterogeneous nodes represent the contextual influences, while connections of homogeneous nodes are inferred from the contextual influences of the other nodes. This tripartite LQB graph is more reliable than any monopartite or bipartite graph in contextual location, query, and Web content recommendations. We validate this LQB graph in an indoor retail scenario with extensive dataset of three logs collected from over 120,000 anonymized, opt-in users over a 1-year period in a large inner-city mall in Sydney, Australia. We characterize the contextual influences that correspond to the arcs in the LQB graph, and evaluate the usefulness of the LQB graph for location, query, and Web content recommendations. The experimental results show that the LQB graph successfully captures the contextual influence and significantly outperforms the state of the art in these applications. Yongli Ren, Martin Tomko 0001, Flora D. Salim, Jeffrey Chan, Charles L. A. Clarke, Mark Sanderson |
IEEE Trans. Knowl. Data Eng. | 3 |
| 2017 | Queue Context Prediction Using Taxi Driver KnowledgeabstractThis paper addresses the problem of taxi-passenger queue context prediction using neighborhood based methods. We capture the taxi drivers' knowledge based on how they move in terms of temporal driver-knowledge deviation (TDKD). Then a TDKD-aided feature importance scheme is introduced for neighborhood based queue context prediction. We apply our proposed scheme to predict different queue contexts at a busy international airport in New York. We argue that the incorporation of taxi drivers' knowledge for calculating feature importance significantly improves the quality of selected neighborhood, thus boosting the prediction accuracy. The experimental results demonstrate the effectiveness of our proposed TDKD-aided feature importance scheme for neighborhood based taxi-passenger queue context prediction. Mohammad Saiedur Rahaman, Margaret Hamilton 0001, Flora D. Salim |
K-CAP | 3 |
| 2017 | Shrink: Distance preserving graph compression
Amin Sadri, Flora D. Salim, Yongli Ren, Masoomeh Zameni, Jeffrey Chan, Timos K. Sellis |
Inf. Syst. | 2 |
| 2017 | CAPRA: A contour-based accessible path routing algorithm
Mohammad Saiedur Rahaman, Yi Mei 0001, Margaret Hamilton 0001, Flora D. Salim |
Inf. Sci. | 4 |
| 2017 | Analyzing Web behavior in indoor retail spacesabstractWe analyze 18‐ million rows of Wi‐Fi access logs collected over a 1‐year period from over 120,000 anonymized users at an inner city shopping mall. The anonymized data set gathered from an opt‐in system provides users' approximate physical location as well as web browsing and some search history. Such data provide a unique opportunity to analyze the interaction between people's behavior in physical retail spaces and their web behavior, serving as a proxy to their information needs. We found that (a) there is a weekly periodicity in users' visits to the mall; (b) people tend to visit similar mall locations and web content during their repeated visits to the mall; (c) around 60% of registered Wi‐Fi users actively browse the web, and around 10% of them use Wi‐Fi for accessing web search engines; (d) people are likely to spend a relatively constant amount of time browsing the web while the duration of their visit may vary; (e) the physical spatial context has a small, but significant, influence on the web content that indoor users browse; and (f) accompanying users tend to access resources from the same web domains. Yongli Ren, Martin Tomko 0001, Flora D. Salim, Kevin Ong, Mark Sanderson |
J. Assoc. Inf. Sci. Technol. | 3 |
| 2016 | UTE: A Ubiquitous Data Exploration Platform for Mobile Sensing ExperimentsabstractIn this paper, we present Ubiquitous data Exploration (UTE), a mobile sensor data collection, annotation and exploration platform. Our platform facilitates rapid prototyping of data mining experiments by using a flexible and do-it-yourself approach. The platform allows researchers to quickly design and deploy applications on mobile devices in order to record sensor data and the corresponding ground-truth information. The platform is supported by a web interface for designing data collection experiments, synchronizing and storing the sensor data with the corresponding labels, and sharing data. Jonathan Liono, Nguyen Cong Thuong, Prem Prakash Jayaraman, Flora D. Salim |
MDM | 4 |
| 2014 | EnviS Tag, Scan, View: A Location-Based App for Visualizing Spatio-temporal Data from Sensor CloudabstractThis paper presents a smartphone app connected to a sensor cloud for spatio-temporal management and 3D visualization of data from ad-hoc wireless sensor networks (WSN) and Internet of Things (IoT). Many existing sensor cloud services and sensor data models do not consider usage for indoors. Although geospatial references, which consist of latitude and longitude, are often included in the data models, these are insufficient for indoor localization of wireless sensor networks. In this paper, we propose a data model for localizing sensors in indoor environment, a sensor cloud framework to manage sensor data as services in the cloud, and an app that includes and visualize sensor data in-situ with 3D visualization of sensor data on floor plans or maps. EnviS is an integrated sensor cloud and app toolkit, prototyped to evaluate this research. EnviS has been tested in three case studies: to manage environmental sensors in indoor spaces, to manage indoor tracking sensors, and to monitor vital signs from wearable wristbands. Flora D. Salim, Mars Dela Pena, Yury Petrov, Nishant Sony, Abdelsalam Ahmed Saad |
MDM (1) | 1 |
| 2004 | Graphical Representation of XML Schema
Flora D. Salim, Rosanne Price, Maria Indrawan, Shonali Krishnaswamy |
APWeb | 1 |