Learning good representations on multi-relational graphs is essential to knowledge base completion (KBC). In this paper, we propose a new self-supervised training objective for multi-relational graph representation learning, via simply incorporating relation prediction into the commonly used 1vsAll objective. The new training objective contains not only terms for predicting the subject and object of a given triple, but also a term for predicting the relation type. We analyse how this new objective impacts multi-relational learning in KBC: experiments on a variety of datasets and models show that relation prediction can significantly improve entity ranking, the most widely used evaluation task for KBC, yielding a 6.1% increase in MRR and 9.9% increase in Hits@1 on FB15k-237 as well as a 3.1% increase in MRR and 3.4% in Hits@1 on Aristo-v4. Moreover, we observe that the proposed objective is especially effective on highly multi-relational datasets, i.e. datasets with a large number of predicates, and generates better representations when larger embedding sizes are used.

Knowledge Base Completion has been a very active area recently, where multiplicative models have generally outperformed additive and other deep learning methods -- like GNN, CNN, path-based models. Several recent KBC papers propose architectural changes, new training methods, or even a new problem reformulation. They evaluate their methods on standard benchmark datasets - FB15k, FB15k-237, WN18, WN18RR, and Yago3-10. Recently, some papers discussed how 1-N scoring can speed up training and evaluation. In this paper, we discuss how by just applying this training regime to a basic model like Complex gives near SOTA performance on all the datasets -- we call this model COMPLEX-V2. We also highlight how various multiplicative methods recently proposed in literature benefit from this trick and become indistinguishable in terms of performance on most datasets. This paper calls for a reassessment of their individual value, in light of these findings.

This is crucial for the use of large Knowledge bases in many downstream applications. However explaining the predictions given by a KBC algorithm is quite important for several real world use cases. For example in rec-ommender systems, a knowledge graph of users, items and their interactions are used to recommend an item to a user based on the users interactions on several items. The ability to explain and reason on the decision is of critical importance to add knowledge to recommender systems. Similarly in a knowledge graph consisting human biological data such as genes, drugs, symptoms and diseases, it is crucial to know which gene and symptoms were involved in predicting a drug for a disease. This requires automatic extraction and ranking of multi-hop paths between a given source and a target entity from a knowledge graph. Previous work has focused on using path information in knowledge graphs for KBC known as path-based inference (Lao et al., 2011; Gardner et al., 2014; Neelakantan et al., 2015; Das et al., 2017b), in which a model is trained to predict missing links between a given pair of entities taking as input several paths that existed between them. Paths are ranked according to a scoring method and used as features to train the model. Embedding-based inference models (Bordes et al., 2013; Lin et al., 2015; Nickel et al., 2011; Socher et al., 2013; Trouillon et al., 2016) for KBC learn entity and relation embeddings by solving an optimization problem that maximises the plausibility of known facts in the knowledge graph.

In logic-based approaches to reasoning tasks such as Recognizing Textual Entailment (RTE), it is important for a system to have a large amount of knowledge data. However, there is a tradeoff between adding more knowledge data for improved RTE performance and maintaining an efficient RTE system, as such a big database is problematic in terms of the memory usage and computational complexity. In this work, we show the processing time of a state-of-the-art logic-based RTE system can be significantly reduced by replacing its search-based axiom injection (abduction) mechanism by that based on Knowledge Base Completion (KBC). We integrate this mechanism in a Coq plugin that provides a proof automation tactic for natural language inference. Additionally, we show empirically that adding new knowledge data contributes to better RTE performance while not harming the processing speed in this framework.