VLDB 2026 Research / reviewers in the wild / expert
Chen Hajaj
dblp:133/1819
· DBLP profile ↗
36ranked-venue papers
8as first author
24since 2021 · last 2026
0000-0001-9940-5654ORCID · verified
Domains — the database's venue-derived domains; a paper can count in several
Artificial intelligence and machine learning · 15 · 8 first-author · 7 since 2021Computer networks · 8 · 8 since 2021Graphics, computer vision, multimedia, augmented reality and games · 7 · 4 first-author · 2 since 2021Security and privacy · 5 · 3 since 2021Human-computer interaction and ubiquitous computing · 2 · 1 since 2021Applied, interdisciplinary, general and emerging computing · 2 · 1 since 2021Software engineering, systems software and programming languages · 1 · 1 since 2021Databases, data management, data science and information retrieval · 1Theory of computation · 1 · 1 first-author
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2026 | Cloudy with a Chance of Anomalies: Dynamic Graph Neural Network for Early Detection of Cloud Services' User AnomaliesabstractIn today’s digital landscape, ensuring the security of cloud environments is critical for organizational resilience, growth, and operational efficiency. As cloud services become more prevalent, so do sophisticated attacks targeting cloud users, making early detection essential. This paper introduces a novel time-based embedding approach for Cloud Services Graph-based Anomaly Detection (CS-GAD) that leverages a Graph Neural Network (GNN) to detect anomalous user behavior. We propose a dynamic tripartite graph to model interactions among users, actions, and cloud services over time. Using behavioral patterns, our GNN generates user embeddings to enable early detection of anomalies. We evaluate this approach on a novel dataset simulating five real-world attacks: cryptojacking, billing abuse, lateral movement, monitor exploitation, and service targeting. The dataset comprises 107,116 Application Programming Interface (API) calls over 32 days, tracking 79 AWS services, with attacks embedded within legitimate cloud traffic. Our results demonstrate that the proposed method achieves a lower false positive rate and higher detection accuracy than a prevailing method, as evidenced by improved accuracy, precision, recall, and F1-score. Revital Marbel, Yanir Cohen, Ran Dubin, Amit Dvir, Chen Hajaj |
CCNC | 5 |
| 2026 | Quality of Experience Prediction for First-Person Shooter Online Gaming: The Case Study of Call of DutyabstractLatency is the most impactful on fairness and Quality of Experience (QoE) in First-Person Shooter (FPS) games. High latency degrades the QoE of players, who may leave the game if unsatisfied with their QoE. Modern FPS games make great efforts to maintain an excellent QoE even under a poor Internet connection with high latency. Those efforts include the wide distribution of game servers and many software optimizations to smooth the effect of lags in the games. This study aims to provide insights into QoE estimation for network-intensive applications by examining one of the most prominent FPS games of the past two decades: Call of Duty. We observed that the game dynamically adjusts its network traffic behavior, including packet size and transmission rate, in response to variations in network quality. However, the ISP does not have this capability since the network traffic is encrypted; observing the game’s network traffic does not expose its nature and most certainly does not expose the game player’s intensity, latency, or QoE. We propose a novel technique for estimating latency and QoE in FPS games from an ISP-level perspective. In our evaluation, the model detected problematic latency in near real-time with 81% accuracy and an 80% F1 on a 10-second window, highlighting a trade-off between responsiveness and predictive performance. The dataset generated for this study is publicly available to support further research. Yehonatan Zion, Eyal Paz, Ran Dubin, Amit Dvir, Chen Hajaj |
CCNC | 5 |
| 2026 | Uncovering Microservice Faults: A Temporal Graph Approach to Root Cause Analysis
Udi Aharon, Amit Dvir, Ran Dubin, Revital Marbel, Chen Hajaj |
ICC | 5 |
| 2026 | GraphMux: A graph-based framework for encrypted traffic classificationabstractThe growing dominance of encrypted network traffic and modern encryption protocols (TLS 1.3, QUIC, DoH) poses significant challenges for accurate network classification, particularly as many existing approaches rely on text- or image-based representations, which fail to adequately capture the inherent structural relationships present in network communication—relationships that are more naturally represented as graphs. In this work, we introduce GraphMux, a graph-based framework that leverages line graph transformations to fuse multiple graph views into a unified representation. We also present three graph-based flow representations (TIG+Chain, StarBurst, and 2Chain) designed to capture both temporal burst dynamics and client–server interaction patterns, using only packet time, direction, and length information, without incorporating any unencrypted statistical features. We evaluate our approach on three datasets: two academic datasets (UTMobileNetTraffic2021 and QUIC PCAP) and a commercial dataset (Flash), using four graph embedding architectures. Across all datasets, GraphMux consistently achieves superior performance, and the proposed graph constructions often yield the best results. Additional experiments examining attribute-selection strategies reveal a strong positive relationship between well-aligned feature assignments and classification accuracy, underscoring the importance of principled attribute design when constructing graph representations for encrypted traffic. Matan Klein, Revital Marbel, Chen Hajaj, Ran Dubin, Amit Dvir |
Comput. Networks | 3 |
| 2026 | The sound of emotions: an artificial intelligence approach to predicting emotions from musical selectionsabstractAbstract Music in the current digital era is consumed primarily on-demand, for example by streaming from Spotify or YouTube, rather than by broadcasting, for example, by listening to a radio station. A strong correlation has been found between music and emotions. Hence, with our ability to select our own music and the availability of artificial intelligence (AI) tools, the importance of music emotion recognition (MER) is significant. This research proposes a novel methodology for predicting emotions from a musical piece that is selected by the listener based on a two-layer AI. The dataset and the process are exceptional in two ways: first, by their qualitative character, which minimized the inherent subjectivity of self-reported emotions, and also the high reliability of the collected data in comparison to other methods such as a questionnaire; and second, by their quantitative character, given $$\:n=\text{9,090}$$ songs from about 4,447 people. The model succeeded in predicting the primary emotion with $$\:accuracy=57\%$$ and one of the two leading emotions (the primary and the secondary) with $$\:accuracy=75.1\%$$ , and without accommodating demographic factors in the model. We believe this knowledge may be a useful tool for therapists, coaches, teachers, etc. and may also raise public awareness of a potential privacy violation. Ron S. Hirschprung, Ori Leshman, Chen Hajaj |
Multim. Syst. | 3 |
| 2025 | Out-Of-Distribution Is Not Magic: The Clash Between Rejection Rate and Model SuccessabstractRecent advancements in Internet protocols, including DNS over HTTPS (DoH) and Encrypted Service Name Indicators (ESNI), are making traditional Deep Packet Inspection (DPI) engines obsolete.Consequently, there is a growing need for nextgeneration traffic classification using artificial intelligence (AI).While DPI automatically categorizes unknown traffic as 'other,' AI-based models cannot automatically handle unknown or Outof-Distribution (OOD) traffic.AI models must effectively detect and classify OOD traffic to ensure robustness, reliability, and accuracy in real-world applications; however, current research often fails to address the challenges of OOD detection.In this paper, we evaluate various state-of-the-art OOD detection techniques for internet traffic classification and explore the drawbacks and advantages of using different threshold levels for the model's tolerance for OOD.Our findings reveal that varying rejection rates have distinct effects on OOD techniques, leading to a change in the optimal strategy for achieving dependable and precise detection across diverse OOD scenarios.We demonstrate that adjusting rejection rates from 10% to 30% can significantly improve the True Detection Rate (TDR) by up to 50%, while the False Detection Rate (FDR) may increase by less than 10%.Moreover, we emphasize that rejection-rate-based evaluation is pivotal for next-generation flow classification, promising a substantial reduction in FDR through rigorous methodological assessment. Itay Meiri, Ran Dubin, Amit Dvir, Chen Hajaj |
FedCSIS | 4 |
| 2025 | Optimized File Type Detection and One-Shot RetrievalabstractFile type classification is critical in digital forensics, and file carving. However, the increasing diversity of file formats challenges accurate classification. Traditional methods rely on hand-crafted features or compact neural networks but face long training times, limited training data, and lower accuracy. This paper introduces three novel, content-based file-type classification approaches to address these challenges. These approaches improve accuracy and streamline the integration of new file types using pre-trained models, enhancing both speed and reliability. The first approach utilizes Natural Language Processing (NLP) with a transformer architecture, while the second combines statistical features with a pre-trained model via transfer learning. These methods achieved accuracy rates of 72.4 % and 69.2 %, respectively, surpassing state-of-the-art Convolutional Neural Network (CNN) models. The third approach employs one-shot learning, achieving 100 % accuracy in several scenarios, enabling efficient training with minimal data. Simona Lisker, Ayelet Butman, Chen Hajaj, Ran Dubin, Amit Dvir |
ICC | 3 |
| 2025 | PQClass: Classification of Post-Quantum Encryption Applications in Internet TrafficabstractPost-quantum cryptography (PQC) is expected to revolutionize secure communications in next-generation digital ecosystems. Previous and ongoing activities demonstrate that different PQC algorithms significantly impact traffic latency, but they do not yet provide a scheme to assess the existence of the PQC algorithm or its identification when encrypted traffic is analyzed for traffic engineering purposes. Hence, this work is the first to propose a novel PQClass pipeline for classifying encrypted Internet traffic of recently NIST-approved PQC algorithms. Hence, it establishes solid grounds for enabling engineers to optimize their networks and, in parallel, for cybersecurity practitioners to familiarise themselves with PQC algorithmic properties for enhancing or devising security architectures in diverse setups. Our pipeline demonstrates impressive performance on real-world data, achieving 86% accuracy in detecting the presence of a PQC algorithm and 91% and 98% accuracy in identifying the browser and OS, respectively, based on PQC-based traffic. Angelos K. Marnerides, Chen Hajaj, Revital Marbel, Ran Dubin, Amit Dvir |
ICC | 2 |
| 2025 | A New D-MAGIC: Dynamic Model for Cybersecurity Attack Detection Using GNNs into ClusteringabstractThe increasing sophistication and frequency of cyberattacks have made Network Intrusion Detection Systems (NIDS) a critical component of modern cybersecurity. This work presents D-MAGIC, a novel real-time NIDS that leverages zero-shot learning and graph-based dynamic clustering to detect known and unknown threats. Unlike traditional systems that rely on labeled datasets and predefined attack signatures, D-MAGIC operates unsupervised, identifying anomalies by detecting deviations from normal network behavior. By embedding the relationships between network flows into a graph structure and dynamically clustering similar patterns, D-MAGIC can detect coordinated attacks and emerging threats with minimal delay. Experimental results on the CIC-IDS-2017 and CSE-CIC-IDS-2018 datasets demonstrate that D-MAGIC achieves an improvement of up to 12 % based on the standard F1 score compared to state-of-the-art methods, while significantly reducing false positives and ensuring rapid, real-time detection with minimal detection latency. Zohar Simhon, Matan Weiss, Chen Hajaj, Revital Marbel, Ran Dubin, Amit Dvir |
ICC | 3 |
| 2025 | Enhancing Encrypted Internet Traffic Classification Through Advanced Data Augmentation TechniquesabstractThe increasing popularity of online services has made Internet Traffic Classification a critical field of study. However, the rapid development of internet protocols and encryption limits usable data availability. This paper addresses the challenges of classifying encrypted Internet Traffic, focusing on the scarcity of open-source datasets and limitations of existing ones. We propose two Data Augmentation (DA) techniques to synthetically generate data based on real samples: Average augmentation and MTU augmentation. Both augmentations are aimed to improve the performance of the classifier, each from a different perspective: The Average augmentation aims to increase dataset size by generating new synthetic samples, while the$M T U$augmentation enhances classifier robustness to varying Maximum Transmission Units (MTUs). Our experiments, conducted on two well-known academic datasets and a commercial dataset, demonstrate the effectiveness of these approaches in improving model performance and mitigating constraints associated with limited and homogeneous datasets. Our findings underscore the potential of data augmentation in addressing the challenges of modern Internet Traffic classification. Specifically, we show that our augmentation techniques significantly enhance encrypted traffic classification models. This improvement can positively impact user Quality of Experience (QoE) by more accurately classifying traffic as video streaming (e.g., YouTube) or chat (e.g., Google Chat). Additionally, it can enhance Quality of Service (QoS) for file downloading activities (e.g., Google Docs). Yehonatan Zion, Porat Aharon, Ran Dubin, Amit Dvir, Chen Hajaj |
ICC | 5 |
| 2025 | A classification-by-retrieval framework for few-shot anomaly detection to detect API injection
Udi Aharon, Ran Dubin, Amit Dvir, Chen Hajaj |
Comput. Secur. | 4 |
| 2024 | Hidden in Time, Revealed in Frequency: Spectral Features and Multiresolution Analysis for Encrypted Internet Traffic ClassificationabstractIn recent years, privacy and security concerns have led to the wide adoption of encrypted protocols, making encrypted traffic a major portion of overall communications online. The transition into more secure protocols poses significant challenges for internet service providers to utilize traditional traffic classification techniques in order to guarantee the Quality of Service (QoS), Quality of Experience (QoE), and cyber-security of their customers. In this work, we introduce two methods, namely STFT-TC and DWT-TC, leveraging compact time-series representation coupled with well-known techniques from the field of Digital Signal Processing (DSP): the short-time Fourier transform (STFT) and the discrete wavelet transform (DWT). The STFT-TC method extracts a suite of statistical and spectral features from the magnitude spectrogram, offering a fresh perspective on interpreting and classifying encrypted traffic. The DWT-TC method extracts statistical features from the wavelet coefficients and incorporates unique characteristics that describe the signal's shape and energy distribution. Evaluating our methods on two public QUIC datasets demonstrated improvements in accuracy of up to 5.7%. Similarly, the F1-scores also showed enhancements, with increments of up to 5.9% for the same datasets. Nathan Dillbary, Roi Yozevitch, Amit Dvir, Ran Dubin, Chen Hajaj |
CCNC | 5 |
| 2024 | WIP: Exploring the Role of Sentiment in Tutor-Student Interaction. The Case Study of CS and Architecture Formative Studio CritiquesabstractThis work-in-progress research presents a novel approach to assessing tutor-student interactions in design studio critiques, thereby advancing studio assessment methodologies. Following constructivist theories, students learn by practicing professional design behaviors. They introduce new concepts and progress according to the tutor's feedback and demonstration. Despite their principal role, critique interactions are often tutor-centric and ambiguous, resulting in negative sentiments that may hinder participation. Current methods measure solely learners' performance of design practices while neglecting the cognitive actions involved, such as the learner's sentiment. This gap limits assessing the effectiveness of the interaction. In this study, we measure the effect of sentiment on introducing new design concepts, identified as first occurrences (FOs). We demonstrate the approach in two natural case studies comprising six critiques of three CS students and three Architecture students. NLP algorithms are developed to quantify the distribution of FOs generated by students and tutors within positive and negative sentiment environments. Changes in the sentiment throughout critiques measure the temporal role of sentiment in generating FOs. Observations exhibit differences in sentiment between CS and Architecture students. In both courses, more learner-centric FOs occurred in a positive sentiment environment. Using explicit assessment methods opens new possibilities for establishing real-time feedback systems, leading studio-based education to its next step in reshaping constructivist pedagogy. Hadas Sopher, Chen Hajaj, John S. Gero |
FIE | 2 |
| 2024 | OSF-EIMTC: An open-source framework for standardized encrypted internet traffic classification
Ofek Bader, Adi Lichy, Amit Dvir, Ran Dubin, Chen Hajaj |
Comput. Commun. | 5 |
| 2024 | Extending limited datasets with GAN-like self-supervision for SMS spam detection
Or Haim Anidjar, Revital Marbel, Ran Dubin, Amit Dvir, Chen Hajaj |
Comput. Secur. | 5 |
| 2024 | Measuring flight-destination similarity: A multidimensional approach
Anat Goldstein, Chen Hajaj |
Expert Syst. Appl. | 2 |
| 2024 | The art of time-bending: Data augmentation and early prediction for efficient traffic classification
Chen Hajaj, Porat Aharon, Ran Dubin, Amit Dvir |
Expert Syst. Appl. | 1 |
| 2023 | When a RF beats a CNN and GRU, together - A comparison of deep learning and classical machine learning approaches for encrypted malware traffic classification
Adi Lichy, Ofek Bader, Ran Dubin, Amit Dvir, Chen Hajaj |
Comput. Secur. | 5 |
| 2023 | Speech and multilingual natural language framework for speaker change detection and diarization
Or Haim Anidjar, Yannick Estève, Chen Hajaj, Amit Dvir, Itshak Lapidot |
Expert Syst. Appl. | 3 |
| 2023 | Breaking the structure of MaMaDroid
Harel Berger, Amit Dvir, Enrico Mariconti, Chen Hajaj |
Expert Syst. Appl. | 4 |
| 2022 | MalDIST: From Encrypted Traffic Classification to Malware Traffic Detection and ClassificationabstractThe world of malware is shifting towards using encrypted traffic. While encryption improves the privacy of users, it brings challenges in the fields of QoS, QoE, and cybersecurity. Recent state-of-the-art Deep-Learning architectures for encrypted traffic classifications demonstrated superb results in tasks of traffic categorization over encrypted traffic. In this paper, we leverage the feasibility to use such architectures for the tasks of malware detection and classification to gain insights into how well these architectures perform in the domain of malware traffic. Specifically, we present a Deep-Learning model for malware traffic detection and classification (MalDIST), which outperforms both classical ML and DL malware traffic classification models both in terms of detection and classification. Ofek Bader, Adi Lichy, Chen Hajaj, Ran Dubin, Amit Dvir |
CCNC | 3 |
| 2021 | PCL: Packet Classification with Limited KnowledgeabstractWe introduce a novel representation of packet classifiers allowing to operate on partially available input data varying dynamically. For a given packet classifier, availability of fields or complexity of field computations, and free target specific resources, the proposed infrastructure computes a classifier representation satisfying performance and robustness requirements. We show the feasibility to reconstruct a classification result in this noisy environment, allowing for the improvement of performance and the achievement of additional robustness levels of network infrastructure. Our results are supported by extensive evaluations in various settings where only a partial input is available. Vitalii Demianiuk, Chen Hajaj, Kirill Kogan |
INFOCOM | 2 |
| 2021 | A Thousand Words are Worth More Than One Recording: Word-Embedding Based Speaker Change Detection
Or Haim Anidjar, Itshak Lapidot, Chen Hajaj, Amit Dvir |
Interspeech | 3 |
| 2021 | Hybrid Speech and Text Analysis Methods for Speaker Change DetectionabstractSpeaker Change Detection (SCD) is the task of segmenting an input audio-recording according to speaker interchanges. Nowadays, many applications, such as Speaker Diarization (SD) or automatic vocal transcription, depend on this segmentation task. In this paper, we focus on the essential task of the SD problem, the audio segmenting process, and suggest a solution for the SCD problem, as well as the assignment of clustered speaker labels for the extracted segments, and applying the solution over two datasets: a commercial dataset in Hebrew and the ICSI Meeting Corpus. As such, we propose a hybrid framework for the SCD problem that is learned by textual information and speech signals and the meta-data features that can be extracted from them. Moreover, we demonstrate the negative correlation between an increase in the number of speakers in the training dataset and the influence on the overall diarization system's performance, which is improved using our efficient SCD component. Finally, we show how our proposed hybrid framework remains robust compared to the ICSI Meeting Corpus, as the experimental evaluation's training and testing is based on two languages. Or Haim Anidjar, Itshak Lapidot, Chen Hajaj, Amit Dvir, Issachar Gilad |
IEEE ACM Trans. Audio Speech Lang. Process. | 3 |
| 2020 | Encrypted video traffic clustering demystified
Amit Dvir, Angelos K. Marnerides, Ran Dubin, Nehor Golan, Chen Hajaj |
Comput. Secur. | 5 |
| 2019 | Improving Robustness of ML Classifiers against Realizable Evasion Attacks Using Conserved Features
Liang Tong, Bo Li 0026, Chen Hajaj, Chaowei Xiao, Ning Zhang 0017, Yevgeniy Vorobeychik |
USENIX Security Symposium | 3 |
| 2018 | Crowdsourcing Clinical Chart Reviews
Joseph R. Coco, Cheng Ye 0001, Chen Hajaj, Yevgeniy Vorobeychik, Joshua C. Denny, Laurie L. Novak, Bradley A. Malin, Thomas A. Lasko, Daniel Fabbri |
AMIA | 3 |
| 2018 | Adversarial Task AssignmentabstractThe problem of task assignment to workers is of long-standing fundamental importance. Examples of this include the classical problem of assigning computing tasks to nodes in a distributed computing environment, assigning jobs to robots, and crowdsourcing. Extensive research into this problem generally addresses important issues such as uncertainty and incentives. However, the problem of adversarial tampering with the task assignment process has not received as much attention. We are concerned with a particular adversarial setting in task assignment where an attacker may target a set of workers in order to prevent the tasks assigned to these workers from being completed. For the case when all tasks are homogeneous, we provide an efficient algorithm for computing the optimal assignment. When tasks are heterogeneous, we show that the adversarial assignment problem is NP-Hard, and present an algorithm for solving it approximately. Our theoretical results are accompanied by extensive simulation results showing the effectiveness of our algorithms. Chen Hajaj, Yevgeniy Vorobeychik |
IJCAI | 1 |
| 2017 | Enhancing Crowdworkers' VigilanceabstractThis paper presents methods for improving the attention span of workers in tasks that heavily rely on their attention to the occurrence of rare events. The underlying idea in our approach is to dynamically augment the task with some dummy (artificial) events at different times throughout the task, rewarding the worker upon identifying and reporting them. The proposed approach is an alternative to the traditional approach of exclusively relying on rewarding the worker for successfully identifying the event of interest itself. We propose three methods for timing the dummy events throughout the task. Two of these methods are static and determine the timing of the dummy events at random or uniformly throughout the task. The third method is dynamic and uses the identification (or misidentification) of dummy events as a signal for the worker's attention to the task, adjusting the rate of dummy events generation accordingly. Avshalom Elmalech, David Sarne, Esther David, Chen Hajaj |
IJCAI | 4 |
| 2017 | Enhancing comparison shopping agents through ordering and gradual information disclosure
Chen Hajaj, Noam Hazon, David Sarne |
Auton. Agents Multi Agent Syst. | 1 |
| 2017 | Selective opportunity disclosure at the service of strategic information platforms
Chen Hajaj, David Sarne |
Auton. Agents Multi Agent Syst. | 1 |
| 2016 | Extending Workers' Attention Span Through Dummy EventsabstractThis paper studies a new paradigm for improving the attention span of workers in tasks that heavily rely on user's attention to the occurrence of rare events. Such tasks are highly common, ranging from crime monitoring to controlling autonomous complex machines, and many of them are ideal for crowdsourcing. The underlying idea in our approach is to dynamically augment the task with some dummy (artificial) events at different times throughout the task, rewarding the worker upon identifying and reporting them. This, as an alternative to the traditional approach of exclusively relying on rewarding the worker for successfully identifying the event of interest itself. We propose three methods for timing the dummy events throughout the task. Two of these methods are static and determine the timing of the dummy events at random or uniformly throughout the task. The third method is dynamic and uses the identification (or misidentification) of dummy events as a signal for the worker's attention to the task, adjusting the rate of dummy events generation accordingly. We use extensive experimentation to compare the methods with the traditional approach of inducing attention through rewarding the identification of the event of interest and within the three. The analysis of the results indicates that with the use of dummy events a substantially more favorable tradeoff between the detection (of the event of interest) probability and the expected expense can be achieved, and that among the three proposed method the one that decides on dummy events on the fly is (by far) the best. Avshalom Elmalech, David Sarne, Esther David, Chen Hajaj |
HCOMP | 4 |
| 2015 | Strategy-Proof and Efficient Kidney Exchange Using a Credit MechanismabstractWe present a credit-based matching mechanism for dynamic barter markets — and kidney exchange in particular — that is both strategy proof and efficient, that is, it guarantees truthful disclosure of donor-patient pairs from the transplant centers and results in the maximum global matching. Furthermore, the mechanism is individually rational in the sense that, in the long run, it guarantees each transplant center more matches than the center could have achieved alone. The mechanism does not require assumptions about the underlying distribution of compatibility graphs — a nuance that has previously produced conflicting results in other aspects of theoretical kidney exchange. Our results apply not only to matching via 2-cycles: the matchings can also include cycles of any length and altruist-initiated chains, which is important at least in kidney exchanges. The mechanism can also be adjusted to guarantee immediate individual rationality at the expense of economic efficiency, while preserving strategy proofness via the credits. This circumvents a well-known impossibility result in static kidney exchange concerning the existence of an individually rational, strategy-proof, and maximal mechanism. We show empirically that the mechanism results in significant gains on data from a national kidney exchange that includes 59% of all US transplant centers. Chen Hajaj, John Dickerson 0001, Avinatan Hassidim, Tuomas Sandholm, David Sarne |
AAAI | 1 |
| 2014 | Ordering Effects and Belief Adjustment in the Use of Comparison Shopping AgentsabstractThe popularity of online shopping has contributed to the development of comparison shopping agents (CSAs) aiming to facilitate buyers' ability to compare prices of online stores for any desired product. Furthermore, the plethora of CSAs in today's markets enables buyers to query more than a single CSA when shopping, thus expanding even further the list of sellers whose prices they obtain. This potentially decreases the chance of a purchase based on the prices outputted as a result of any single query, and consequently decreases each CSAs' expected revenue per-query. Obviously, a CSA can improve its competence in such settings by acquiring more sellers' prices, potentially resulting in a more attractive ``best price''. In this paper we suggest a complementary approach that improves the attractiveness of a CSA by presenting the prices to the user in a specific intelligent manner, which is based on known cognitive-biases.The advantage of this approach is its ability to affect the buyer's tendency to terminate her search for a better price, hence avoid querying further CSAs, without having the CSA spend any of its resources on finding better prices to present.The effectiveness of our method is demonstrated using real data, collected from four CSAs for five products. Our experiments with people confirm that the suggested method effectively influence people in a way that is highly advantageous to the CSA. Chen Hajaj, Noam Hazon, David Sarne |
AAAI | 1 |
| 2014 | Strategic information platforms: selective disclosure and the price of "free"abstractThis paper deals with platforms that provide agents easier access to the type of opportunities in which they are interested (e.g., eCommerce platforms, used cars bulletins and dating web-sites). We show that under various common service schemes, a platform can benefit from not necessarily listing all the opportunities with which it is familiar, even if there is no marginal cost for listing any additional opportunity. The main implication of this result is that platforms should extract their expected-profit-maximizing service terms not based solely on the fees charged from users, but they should also use the subset that will be listed as the decision variable in the optimization problem. The analysis applies to four well-known service schemes that a platform may use to price its services. We show that neither of these schemes generally dominates the others or is dominated by any of the others. For the common case of homogeneous preferences, however, several dominance relationships can be proved, enabling the platform to identify the schemes that should be used as a default. Furthermore, the analysis provides a game-theoretic search-based explanation for a possible preference of buyers to pay for the service rather than receive it for free (e.g., when the service is sponsored by ads), a phenomena that has been justified in prior literature typically with the argument of willingness to pay a premium for an ad-free experience or more reliable platforms. The paper shows that this preference can hold both for the users and the platform in a given setting, even if both sides are fully strategic. Chen Hajaj, David Sarne |
EC | 1 |
| 2013 | Search More, Disclose LessabstractThe blooming of comparison shopping agents (CSAs) in recent years enables buyers in today's markets to query more than a single CSA while shopping, thus substantially expanding the list of sellers whose prices they obtain. From the individual CSA point of view, however, the multi-CSAs querying is definitely non-favorable as most of today's CSAs benefit depends on payments they receive from sellers upon transferring buyers to their websites (and making a purchase). The most straightforward way for the CSA to improve its competence is through spending more resources on getting more sellers' prices, potentially resulting in a more attractive ``best price''. In this paper we suggest a complementary approach that improves the attractiveness of the best price returned to the buyer without having to extend the CSAs' price database. This approach, which we term ``selective price disclosure'' relies on removing some of the prices known to the CSA from the list of results returned to the buyer. The advantage of this approach is in the ability to affect the buyer's beliefs regarding the probability of obtaining more attractive prices if querying additional CSAs. The paper presents two methods for choosing the subset of prices to be presented to a fully-rational buyer, attempting to overcome the computational complexity associated with evaluating all possible subsets. The effectiveness and efficiency of the methods are demonstrated using real data, collected from five CSAs for four products. Furthermore, since people are known to have an inherently bounded rationality, the two methods are also evaluated with human buyers, demonstrating that selective price-disclosing can be highly effective with people, however the subset of prices that needs to be used should be extracted in a different (and more simplistic) manner. Chen Hajaj, Noam Hazon, David Sarne, Avshalom Elmalech |
AAAI | 1 |