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A Dynamic Graph Convolutional Network Based on Spatial-Temporal Modeling
LI Jing, LIU Yu, ZOU Lei
Acta Scientiarum Naturalium Universitatis Pekinensis    2021, 57 (4): 605-613.   DOI: 10.13209/j.0479-8023.2021.052
Abstract1676)   HTML    PDF(pc) (829KB)(507)       Save
In order to learn high-level representation with rich information for dynamic graphs where nodes and edges change dynamically, a dynamic graph convolutional network (DyGCN) is proposed to learn representation as a mixture of both spatial and temporal information. The model performs spatial convolutions to learn structural information on graphs and temporal convolutions to learn historical information along time axis. Besides, the selfadapting mechanism on the spatial convolution layer allows model parameters to update with graphs. Extensive experiments on financial networks for edge classification tasks against financial crimes show that DyGCN outperforms state-of-the-art methods.
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A Parallel Algorithm to Answer Shortest Distance on Dynamic Graph
HAN Shuo, ZOU Lei
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (1): 112-122.   DOI: 10.13209/j.0479-8023.2019.113
Abstract1458)   HTML    PDF(pc) (1188KB)(192)       Save
The paper presents a parallel algorithm framework to answer shortest distance queries on dynamic graphs. Based on maintaining a delta graph, multiple queries within a batch are executed in parallel over different versions of data graph by multi-threading. For each query, bidirectional breath-first search (BFS) is utilized to reduce search space. During the search process, an exploration direction decision-making function is proposed. Furthermore, adjacency-lists of data graph are encoded by BSR layout, combined with SIMD instructions and graph reordering algorithm, higher degree of data-level parallelism is achieved. Extensive experiments on real graph datasets confirm the superior efficiency of the proposed solution.
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Regular Path Queries on Large Graph Data
ZHANG Yu, ZENG Li, ZOU Lei
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 236-242.   DOI: 10.13209/j.0479-8023.2017.151
Abstract1470)   HTML3)    PDF(pc) (508KB)(366)       Save

The authors propose a divide-and-conquer based solution over gStore, an existing RDF search engine, to process property path query on large scale graph data. In proposed solution, regular expression is partitioned within the path query and then preprocess strings of fixed length. The authors handle the search over those subqueries of wildcards. The proposed method is able to filter lots of unpromising search and efficient on solving the regular path match problem over large scale graph data. The corresponding experiments on DBpedia and LUBM confirm that proposed method can response for queries in seconds on average.

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Discovering Abnormal Data in RDF Knowledge Base
HE Binbin,ZOU Lei,ZHAO Dongyan
Acta Scientiarum Naturalium Universitatis Pekinensis   
Automatic Understanding of Natural Language Questions for Querying Chinese Knowledge Bases
XU Kun,FENG Yansong,ZHAO Dongyan,CHEN Liwei,ZOU Lei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract811)      PDF(pc) (493KB)(532)       Save
A framework to transform natural language questions into computer-understoodable structured queries is presented. The authors propose to use query semantic graph to represent the semantics in Chinese questions, and adopt predicate and entity disambiguation to match the query graph to the schema of a knowledge base. The authors collect a benchmark of 42 frequently-asked questions randomly sampled from 3 categories of Baidu Knows, including person, location and organization. Experiment results show that proposed framework can effectively convert natural language questions into SPARQL queries, and lay a good foundation for the next generation of intelligent question answering systems.
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