Complex Query Answering (CQA) on knowledge graphs is a fundamental yet challenging task, which can be formalized as answering a subset of first-order logic queries containing logical conjunction, disjunction, negation, and existential quantifiers. Recent research reveals that Link Predictors (LPs) trained on 1-hop queries can generalize to various types of complex queries. However, existing methods neglect crucial characteristics of LPs' outputs, including the effects of highly relevant entities and uncertainty. What's worse, as they model logical operations by fuzzy set operations, these methods suffer from problems like inflexibility, sensitivity to noise, and inconsistency with priority in human cognition, which limits their performance, especially on queries with negation. To address these challenges, we propose an efficient fuzzy system for CQA that requires no extra training overheads and is plug-and-play with existing LP-based methods. Firstly, we expand the output of LPs by two complementary membership functions of weak and strong relevance, which help to distinguish the target entities from highly relevant and irrelevant entities. Subsequently, we model logical operations through fuzzy rule bases and infer the final predictions via defuzzification, providing a flexible and tractable scheme for modeling logical operations. Finally, the effectiveness of the proposed fuzzy system is validated by its outstanding performance on benchmark datasets when compared to state-of-theart methods. The source code of our proposed method is available at https://anonymous.4open.science/r/FuzzSys-CQA-E285.

Due to the easy access, implicit feedback is often used for recommender systems. Compared with point-wise learning and pair-wise learning methods, list-wise rank learning methods have superior performance for top- \(N\) recommendation. Recent solutions, especially the list-wise methods, simply treat all interacted items of a user as equally important positives and annotate all no-interaction items of a user as negatives. For the list-wise approaches, we argue that this annotation scheme of implicit feedback is over-simplified due to the sparsity and missing fine-grained labels of the feedback data. To overcome this issue, we revisit the so-called positive and negative samples. First, considering the loss function of list-wise ranking, we analyze the impact of false positives and negatives theoretically. Second, based on the observation, we propose a self-adjusting credibility weight mechanism to re-weigh the positive samples and exploit the higher-order relation based on item–item matrix to sample the critical negative samples. In order to prevent the introduction of noise, we design a pruning strategy for critical negatives. Besides, to combine the reconstruction loss function for the positive samples and critical negative samples, we develop a simple yet effective VAEs framework with linear structure, which abandons the complex non-linear structure. Extensive experiments are conducted on six public real-world datasets. The results demonstrate that, our VAE* outperforms other VAE-based models by a large margin. Besides, we also verify the effect of denoising positives and exploring critical negatives by ablation study.

This paper proposes a new task in the field of Answering Subjective Induction Question on Products (SUBJPQA). The answer to this kind of question is non-unique, but can be interpreted from many perspectives. For example, the answer to ‘whether the phone is heavy’ has a variety of different viewpoints. A satisfied answer should be able to summarize these subjective opinions from multiple sources and provide objective knowledge, such as the weight of a phone. That is quite different from the traditional QA task, in which the answer to a factoid question is unique and can be found from a single data source. To address this new task, we propose a three-steps method. We first retrieve all answer-related clues from multiple knowledge sources on facts and opinions. The implicit commonsense facts are also collected to supplement the necessary but missing contexts. We then capture their relevance with the questions by interactive attention. Next, we design a reinforcement-based summarizer to aggregate all these knowledgeable clues. Based on a template-controlled decoder, we can output a comprehensive and multi-perspective answer. Due to the lack of a relevant evaluated benchmark set for the new task, we construct a large-scale dataset, named SupQA, consisting of 48,352 samples across 15 product domains. Evaluation results show the effectiveness of our approach.

This article focuses on the topic of multi-hop question generation (QG), which aims to generate the questions requiring multi-hop reasoning skills from the given text. These questions are not only syntactically valid but also logically correlated with the answers. Concretely, we first design a basic QG model and customize several techniques to ensure results' syntactic validity. In order to promote the logical correlations, we use a reasoning chain extracted from the text to regularize the results. Considering that different samples have their own characteristics on the aspects of text contextual structure, the type of question, and logical correlation, we propose a new adaptive meta-learner to optimize the basic QG model. Each case and its similar samples are viewed as a pseudo-QG task. The similar structural contexts contained in the same task are used as guidance to fine-tune the model. To measure the similarity of samples' structured inputs, we propose a data-driven multi-level recognizer. The experimental results on two typical data sets in various domains show the effectiveness of the proposed approach. Moreover, we apply the generated results to the task of machine reading comprehension and achieve significant performance improvements. That demonstrates the capacity of multi-hop QG in facilitating real-world applications.

In spite of its wide usage in various applications, existing construction methods for Knowledge Base (KB) are still on their way to obtaining 100% correct facts. Thus, employing crowd workers to validate a KB has been proposed to improve its reliability. Most of the existing works focus on devising games with proper incentives to engage workers in validating more facts, but rarely consider matching facts with proper workers. Facts have diverse domains (topics), which naturally require workers of different expertise. In addition, they also generally have different utilities, i.e., some are more heavily used than others. Thus, distinguishing the facts in terms of utility to give them different validation priorities is meaningful, especially when the budget is limited. To this end, we study the crowdsourced fact validation problem which considers worker domains and fact utilities, and find that with some reductions, it can be solved by the existing minimum cost network flow method. However, directly employing that method requires a huge time cost. We thereby propose an optimized network flow method which reduces the network complexity to save the time cost by properly grouping the facts. Furthermore, we propose an incremental validation method, which utilizes the previous results for validating an evolving KB. We finally conduct extensive experiments to demonstrate the effectiveness of the proposed methods.

This paper focuses on the topic of multi-hop question generation, which aims to generate questions needed reasoning over multiple sentences and relations to derive answers. In particular, we first build an entity graph to integrate various entities scattered over text based on their contextual relations. We then heuristically extract the sub-graph by the evidential relations and type, so as to obtain the reasoning chain and textual related contents for each question. Guided by the chain, we propose a holistic generator-evaluator network to form the questions, where such guidance helps to ensure the rationality of generated questions which need multi-hop deduction to correspond to the answers. The generator is a sequence-to-sequence model, designed with several techniques to make the questions syntactically and semantically valid. The evaluator optimizes the generator network by employing a hybrid mechanism combined of supervised and reinforced learning. Experimental results on HotpotQA data set demonstrate the effectiveness of our approach, where the generated samples can be used as pseudo training data to alleviate the data shortage problem for neural network and assist to learn the state-of-the-arts for multi-hop machine comprehension.

Numerous consumer reviews of products are now available on the Internet. Consumer reviews contain rich and valuable knowledge for both firms and users. However, the reviews are often disorganized, leading to difficulties in information navigation and knowledge acquisition. This article proposes a product aspect ranking framework, which automatically identifies the important aspects of products from online consumer reviews, aiming at improving the usability of the numerous reviews. The important product aspects are identified based on two observations: 1) the important aspects are usually commented on by a large number of consumers and 2) consumer opinions on the important aspects greatly influence their overall opinions on the product. In particular, given the consumer reviews of a product, we first identify product aspects by a shallow dependency parser and determine consumer opinions on these aspects via a sentiment classifier. We then develop a probabilistic aspect ranking algorithm to infer the importance of aspects by simultaneously considering aspect frequency and the influence of consumer opinions given to each aspect over their overall opinions. The experimental results on a review corpus of 21 popular products in eight domains demonstrate the effectiveness of the proposed approach. Moreover, we apply product aspect ranking to two real-world applications, i.e., document-level sentiment classification and extractive review summarization, and achieve significant performance improvements, which demonstrate the capacity of product aspect ranking in facilitating real-world applications.