This paper proposes a family of Aligned Entropic Graph Kernels (AEGK) for graph classification, based on the Averaged Mixing Matrix (AMM) of Continuous-time Quantum Walks (CTQWs). Specifically, we show how the AMM matrix allows us to compute a quantum Shannon entropy of each vertex for either un-attributed or attributed graphs. For pairwise graphs, the proposed AEGK kernels are defined by computing the kernel-based similarity between the quantum Shannon entropies of their pairwise aligned vertices. Theoretical analysis reveals that the AEGK kernels can not only integrate the structural correspondence information between graphs, but also discriminate the structural differences between aligned vertices. Moreover, the AEGK kernels can simultaneously capture both global and local structural characteristics through the quantum Shannon entropies. These theoretical properties explain the effectiveness.

This paper proposes a family of Hierarchical Aligned Quantum Jensen-Shannon Kernels (HAQJSK) for un-attributed graphs. The HAQJSK kernels can incorporate hierarchical correspondence information between graphs, and thus transform arbitrary sized graphs into fix-sized aligned structures, i.e., the hierarchical transitive aligned Adjacency Matrix of vertices or Density Matrix of Continuous-Time Quantum Walks (CTQWs). For pairwise graphs, the resulting HAQJSK kernels are defined by computing the Quantum Jensen-Shannon Divergence (QJSD) between their aligned structures. Unlike classical graph kernels, the HAQJSK kernels can either reflect global intrinsic structure characteristics through CTQWs, or address the drawback of neglecting structural correspondence information, theoretically explaining the effectiveness.

As large language models (LLMs)-driven conversational systems have advanced, users have become accustomed to engaging in standalone, continuous interactions. In such interactions, users may abruptly change their intent across turns. However, most existing intent detection methods focus on accurately extracting intents and slots from individual utterances, without considering the broader conversational dynamics. This makes them ill-equipped to handle long, evolving conversations where arbitrary intent drift can occur. To address this challenge, we define the intent drift detection task in continuous conversations. We then propose a differentiable method, termed DriftHunter, that enables neural networks to understand how user intent shifts as the conversation progresses via dynamically accumulating the temporal transition across turns. Unlike existing methods, our proposed method incrementally captures global and local transition patterns between intents and slots without relying on prior statistical results. Moreover, our model sequentially accumulates transition patterns across conversation turns. This allows it to learn temporal accumulated dynamics, enabling neural network models to better focus on the most trending user intents during continuous interaction. Experimental evaluations on real-world datasets demonstrate that the proposed method outperforms state-of-the-art baselines in both intent drift detection, intent identification, and slot-filling downstream tasks. Our case study analysis reveals that the learned temporal transition patterns explain the predicted intent drifts.11The source code and dataset are available at https://github.com/FDHTJ/DriftHunter

In this work, we develop a family of Aligned Entropic Graph Kernels (AEGK) for graph classification. We commence by performing the Continuous-time Quantum Walk (CTQW) on each graph structure, and compute the Averaged Mixing Matrix (AMM) to describe how the CTQW visits all vertices from a starting vertex. More specifically, we show how this AMM matrix allows us to compute a quantum Shannon entropy of each vertex for either un-attributed or attributed graphs. For pairwise graphs, the proposed AEGK kernels are defined by computing the kernel-based similarity between the quantum Shannon entropies of their pairwise aligned vertices. The analysis of theoretical properties reveals that the proposed AEGK kernels cannot only address the shortcoming of neglecting the structural correspondence information between graphs arising in most existing R-convolution graph kernels, but also overcome the problems of neglecting the structural differences and vertex-attributed information arising in existing vertex-based matching kernels. Moreover, unlike most existing classical graph kernels that only focus on the global or local structural information of graphs, the proposed AEGK kernels can simultaneously capture both global and local structural characteristics through the quantum Shannon entropies, reflecting more precise kernel-based similarity measures between pairwise graphs. The above theoretical properties explain the effectiveness of the proposed AEGK kernels. Experimental evaluations demonstrate that the proposed kernels can outperform state-of-the-art graph kernels and deep learning models for graph classification.

In this work, we propose two novel quantum walk kernels, namely the Hierarchical Aligned Quantum Jensen-Shannon Kernels (HAQJSK), between un-attributed graph structures. Different from most classical graph kernels, the proposed HAQJSK kernels can incorporate hierarchical aligned structure information between graphs and transform graphs of random sizes into fixed-size aligned graph structures, i.e., the Hierarchical Transitive Aligned Adjacency Matrix of vertices and the Hierarchical Transitive Aligned Density Matrix of the Continuous-Time Quantum Walks (CTQW). With pairwise graphs to hand, the resulting HAQJSK kernels are defined by computing the Quantum Jensen-Shannon Divergence (QJSD) between their transitive aligned graph structures. We show that the proposed HAQJSK kernels not only reflect richer intrinsic whole graph characteristics in terms of the CTQW, but also address the drawback of neglecting structural correspondence information that arises in most R-convolution graph kernels. Moreover, unlike the previous QJSD based graph kernels associated with the QJSD and the CTQW, the proposed HAQJSK kernels can simultaneously guarantee the properties of permutation invariant and positive definiteness, explaining the theoretical advantages of the HAQJSK kernels. The experiment indicates the effectiveness of the new proposed kernels.

To ease the process of building Knowledge Graphs (KGs) from scratch, a cost-effective method is required to enrich a KG using the triples extracted from a corpus. However, it is challenging to enrich a KG with newly extracted triples since they contain noisy information. This paper proposes to refine a KG by leveraging information extracted from a corpus. In particular, we first formulate the task of building KGs as two coupled sub-tasks, namely join event extraction and knowledge graph fusion. We then propose a collaborative knowledge graph fusion framework, which is composed of an explorer and a supervisor, to allow the involved two sub-tasks to mutually assist each other in an alternative manner. More concretely, an explorer extracts triples from a corpus supervised by both the ground-truth annotation and the KG provided by the supervisor. Furthermore, a supervisor then evaluates the extracted triples and enriches the KG with those that are highly ranked. To implement this evaluation, we further propose a translated relation alignment scoring mechanism to align and translate the extracted triples to the KG. Experimental results verify that this collaboration can improve both the performance of our sub-tasks, and contribute to high-quality enriched knowledge graphs.

This paper proposes a new Quantum Spatial Graph Convolutional Neural Network (QSGCNN) model that can directly learn a classification function for graphs of arbitrary sizes. Unlike state-of-the-art Graph Convolutional Neural Network (GCNN) models, the proposed QSGCNN model incorporates the process of identifying transitive aligned vertices between graphs and transforms arbitrary sized graphs into fixed-sized aligned vertex grid structures. In order to learn representative graph characteristics, a new quantum spatial graph convolution is proposed and employed to extract multi-scale vertex features, in terms of quantum information propagation between grid vertices of each graph. Since the quantum spatial convolution preserves the grid structures of the input vertices (i.e., the convolution layer does not alter the original spatial position of vertices), the proposed QSGCNN model allows to directly employ the traditional convolutional neural network architecture to further learn from the global graph topology, providing an end-to-end deep learning architecture that integrates the graph representation and learning in the quantum spatial graph convolution layer and the traditional convolutional layer for graph classifications. We indicate the effectiveness of the proposed QSGCNN model in relation to existing state-of-the-art methods. Experiments on benchmark graph classification datasets demonstrate the effectiveness of the proposed QSGCNN model.

This paper proposes a novel Quantum Spatial Graph Convolutional Neural Network (QSGCNN) model that can directly learn a classification function for graphs of arbitrary sizes. The main idea is to define a new quantum-inspired spatial graph convolution associated with pre-transformed fixed-sized aligned grid structures of graphs, in terms of quantum information propagation between grid vertices of each graph. We show that the proposed QSGCNN model can significantly reduce either the information loss or the notorious tottering problem arising in existing spatially-based Graph Convolutional Network (GCN) models. Experiments on benchmark graph datasets demonstrate the effectiveness of the proposed QSGCNN model.

Counterfactual thinking describes a psychological phenomenon that people re-infer the possible results with different solutions about things that have already happened. It helps people to gain more experience from mistakes and thus to perform better in similar future tasks. This paper investigates the counterfactual thinking for agents to find optimal decision-making strategies in multi-agent reinforcement learning environments. In particular, we propose a multi-agent deep reinforcement learning model with a structure which mimics the human-psychological counterfactual thinking process to improve the competitive abilities for agents. To this end, our model generates several possible actions (intent actions) with a parallel policy structure and estimates the rewards and regrets for these intent actions based on its current understanding of the environment. Our model incorporates a scenario-based framework to link the estimated regrets with its inner policies. During the iterations, our model updates the parallel policies and the corresponding scenario-based regrets for agents simultaneously. To verify the effectiveness of our proposed model, we conduct extensive experiments. Experimental results show that counterfactual thinking can actually benefit the agents to obtain more accumulative rewards from the environments with fair information by comparing to their opponents.

The financial contagion describes a widespread phenomenon of the interdependency for pairs of stock time series during the market abnormality periods. Since the interdependency rule between stocks varies in different periods, it is difficult to capture the interdependency rule for stocks related to the market status effectively. We define this interdependency rule as, the co-movement pattern, a high-dimensional co-varying relationship between pairs of stock time series and propose a Co-movement Attention Model (CAM) to discover the co-movement patterns for the stocks related to the market status. With the discovered patterns, CAM focuses on the stock-level abnormality periods by the co-movement attention automatically. CAM is trained under the supervision of the stock sector label information. CAM has the ability to model financial contagion and detect global market abnormality periods, by modeling co-movement patterns on every pair-wise stocks. We verify our methods on the real-world stock data and compare it with state of the art methods. The experimental result shows that our method not only captures the co-movement attentions with better quantitative metric values but also covers more real market abnormalities than the other alternatives.

Intervention analysis is the common method to reveal relationships between objects in human as well as biological society. Data mining research community is just starting to pay attention to intervention analysis. As the traditional association rules are not successful at measuring intervention, this paper tries to mining intervention rules from time series data of sub-complex system. The main contributions of this study include: (1) introduces a new concept of intervention rules. It can quantitatively detect at what scale, how intensive and how long the intervention does make sense; (2) conduct wavelet transform on time series. The decomposition scale can denotes the intervention scale; (3) proposes a new concept named directional correlation to measure intervention intensity; (4) calculates the intervention intensity between time series data with different time delays. The time delay can uncover after how long the intervention takes place; (5) conducts experiments on real datasets. The results show that intervention rules do exist at different decomposition scale of the original data. Moreover, the number of rules discovered by multi-scale analyzing methods is always 4 or 5 times more than those found by single scale methods. And the stability of rules discovered by the improved multi-scale mining algorithm MMIR* is always 100%, while the stability of rules discovered by the basic multi-scale mining algorithm MMIR fluctuate around 70%.