The use of semantics and semantic technologies for search and retrieval has attracted interests both from academia and industry in recent years. What is now commonly known as Semantic Search is in fact a broad field encompassing ideas and concepts from different areas, including Information Retrieval, Semantic Web and database. This is the fourth edition of the Semantic Search workshop which aims to bring together researchers and practitioners from various communities, to provide a forum for dissemination, discussion, and for the exchange and transfer of knowledge related to the use of semantics for search and retrieval. This year's workshop will continue to push and promote efforts towards an evaluation benchmark for Semantic Search systems.
This paper is concerned with the problems of understanding the relations in automatically extracted semantic datasets such as DBpedia and utilizing them in semantic queries such as SPARQL. Although DBpedia has achieved a great success in supporting convenient navigation and complex queries over the extracted semantic data from Wikipedia, the browsing mechanism and the organization of the relations in the extracted data are far from satisfactory. Some relations have anomalous names and are hard to be understood even by experts if looking at the relation names only; there exist synonymous and polysemous relations which may cause incomplete or noisy query results. In this paper, we propose to solve these problems by 1 exploiting the Wikipedia category system to facilitate relation understanding and query constraint selection, 2 exploring various relation representation models for similar/super-/sub-relation detection to help the users select proper relations in their queries. A prototype system has been implemented and extensive experiments are performed to illustrate the effectiveness of the proposed approach.
Nowadays, more and more knowledge are published in form of RDF triples enriched with numerous types of annotations such as provenance, temporal and geospatial information. Due to the popularity of the ever-growing annotations, graph databases have proposed various...
COVID-19 evolves rapidly and an enormous number of people worldwide desire instant access to COVID-19 information such as the overview, clinic knowledge, vaccine, prevention measures, and COVID-19 mutation. Question answering (QA) has become the mainstream interaction way for users to consume the ever-growing information by posing natural language questions. Therefore, it is urgent and necessary to develop a QA system to offer consulting services all the time to relieve the stress of health services. In particular, people increasingly pay more attention to complex multi-hop questions rather than simple ones during the lasting pandemic, but the existing COVID-19 QA systems fail to meet their complex information needs. In this paper, we introduce a novel multi-hop QA system called COKG-QA, which reasons over multiple relations over large-scale COVID-19 Knowledge Graphs to return answers given a question. In the field of question answering over knowledge graph, current methods usually represent entities and schemas based on some knowledge embedding models and represent questions using pre-trained models. While it is convenient to represent different knowledge (i.e., entities and questions) based on specified embeddings, an issue raises that these separate representations come from heterogeneous vector spaces. We align question embeddings with knowledge embeddings in a common semantic space by a simple but effective embedding projection mechanism. Furthermore, we propose combining entity embeddings with their corresponding schema embeddings which served as important prior knowledge, to help search for the correct answer entity of specified types. In addition, we derive a large multi-hop Chinese COVID-19 dataset (called COKG-DATA for remembering) for COKG-QA based on the linked knowledge graph OpenKG-COVID19 launched by OpenKG①, including comprehensive and representative information about COVID-19. COKG-QA achieves quite competitive performance in the 1-hop and 2-hop data while obtaining the best result with significant improvements in the 3-hop. And it is more efficient to be used in the QA system for users. Moreover, the user study shows that the system not only provides accurate and interpretable answers but also is easy to use and comes with smart tips and suggestions.
In recent years, lots of knowledge graphs built from Wikipedia, the largest multilingual online encyclopedia, have been published on the Web to support var
In this paper, we are the first to construct a software programming taxonomy from Stackoverflow. More precisely, we propose a machine learning based method with novel features to capture the hierarchical semantic structure of tags in Stackoverflow. A graph pruning algorithm is applied to eliminate the conflicts by constructing a Directed Acyclic Graph (DAG). As a result, our dataset, named Software.zhishi.schema, contains 38,205 concepts together with 36,249 subsumption relations. In order to further test the usability of our published data, we adopt a similarity computing task of words from software programming which is one of the most fundamental tasks in the software repository mining area. The results show that our dataset can outperform other knowledge bases due to its high coverage with finergrained domain concepts.
Medical Visual Question Answering (Med-VQA) is a task in the field of Artificial Intelligence where a medical image is given with a related question, and the task is to provide an accurate answer to the question. It involves the integration of computer vision,...
Recently more and more structured data in the form of RDF triples have been published and integrated into Linked Open Data (LOD). While the current LOD contains hundreds of data sources with billions of triples, it has a small number of distinct relations compared...
This book constitutes the thoroughly refereed papers of the 8th Chinese Conference on The Semantic Web and Web Science, CSWS 2014, held in Wuhan, China, in August 2014. The 22 research papers presented were carefully reviewed and selected from 61 submissions. The papers are organized in topical sections such as ontology reasoning and learning; semantic data generation and management; and semantic technology and applications.
Online advertising represents a growing part of the revenues of major Internet service providers such as Google and Yahoo. A commonly used strategy is to place advertisements (ads) on the search result pages according to the users' submitted queries. Relevant ads are likely to be clicked by a user and to increase the revenues of both advertisers and publishers. However, bid phrases defined by ad-owners are usually contained in limited number of ads. Directly matching user queries with bid phrases often results in finding few appropriate ads. To address this shortcoming, query expansion is often used to increase the chances to match the ads. Nevertheless, query expansion on top of the traditional inverted index faces efficiency issues such as high time complexity and heavy I/O costs. Moreover, precision cannot always be improved, sometimes even hurt due to the involvement of additional noise. In this paper, we propose an efficient ad search solution relying on a block-based index able to tackle the issues associated with query expansion. Our index structure places clusters of similar bid phrases in corresponding blocks with their associated ads. It reduces the number of merge operations significantly during query expansion and allows sequential scans rather than random accesses, saving I/O costs. We adopt flexible block sizes according to the clustering results of bid phrases to further optimize the index structure for efficient ad search. The pre-computation of such clusters is achieved through an agglomerative iterative clustering algorithm. Finally, we adapt the spreading activation mechanism to return the top-k relevant ads, improving search precision. The experimental results of our prototype, AdSearch, show that we can indeed return a larger number of relevant ads without sacrificing execution speed.