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We study the (non-uniform) quantified constraint satisfaction problem QCSP(H) as H ranges over partially reflexive cycles. We obtain a complexity-theoretic dichotomy: QCSP(H) is either in NL or is NP-hard. The separating conditions are…

Computational Complexity · Computer Science 2013-03-04 Florent Madelaine , Barnaby Martin

We analyze knowledge-based visual question answering, for which given a question, the models need to ground it into the visual modality and retrieve the relevant knowledge from a given large knowledge base (KB) to be able to answer. Our…

Artificial Intelligence · Computer Science 2024-04-17 Elham J. Barezi , Parisa Kordjamshidi

Knowledge base question answering (KBQA) aims to answer a question over a knowledge base (KB). Recently, a large number of studies focus on semantically or syntactically complicated questions. In this paper, we elaborately summarize the…

Computation and Language · Computer Science 2021-05-26 Yunshi Lan , Gaole He , Jinhao Jiang , Jing Jiang , Wayne Xin Zhao , Ji-Rong Wen

Knowledge Graph Question Answering (KGQA) aims to answer user-questions from a knowledge graph (KG) by identifying the reasoning relations between topic entity and answer. As a complex branch task of KGQA, multi-hop KGQA requires reasoning…

Computation and Language · Computer Science 2022-11-15 Weiqiang Jin , Biao Zhao , Hang Yu , Xi Tao , Ruiping Yin , Guizhong Liu

The multi-relational Knowledge Base Question Answering (KBQA) system performs multi-hop reasoning over the knowledge graph (KG) to achieve the answer. Recent approaches attempt to introduce the knowledge graph embedding (KGE) technique to…

Computation and Language · Computer Science 2021-11-01 Guanglin Niu , Yang Li , Chengguang Tang , Zhongkai Hu , Shibin Yang , Peng Li , Chengyu Wang , Hao Wang , Jian Sun

Phase transitions in combinatorial problems have recently been shown to be useful in locating "hard" instances of combinatorial problems. The connection between computational complexity and the existence of phase transitions has been…

Computational Complexity · Computer Science 2016-11-17 Gabriel Istrate

Organisations store huge amounts of data from multiple heterogeneous sources in the form of Knowledge Graphs (KGs). One of the ways to query these KGs is to use SPARQL queries over a database engine. Since SPARQL follows exact match…

Databases · Computer Science 2017-11-22 Madhulika Mohanty , Maya Ramanath , Mohamed Yahya , Gerhard Weikum

Knowledge bases (KB), both automatically and manually constructed, are often incomplete --- many valid facts can be inferred from the KB by synthesizing existing information. A popular approach to KB completion is to infer new relations by…

Computation and Language · Computer Science 2019-01-01 Rajarshi Das , Shehzaad Dhuliawala , Manzil Zaheer , Luke Vilnis , Ishan Durugkar , Akshay Krishnamurthy , Alex Smola , Andrew McCallum

In this paper we explore fundamental concepts in computational complexity theory and the boundaries of algorithmic decidability. We examine the relationship between complexity classes \textbf{P} and \textbf{NP}, where $L \in \textbf{P}$…

Computational Complexity · Computer Science 2025-12-30 Duaa Abdullah , Jasem Hamoud

Answering complex questions over knowledge bases (KB-QA) faces huge input data with billions of facts, involving millions of entities and thousands of predicates. For efficiency, QA systems first reduce the answer search space by…

Information Retrieval · Computer Science 2022-04-05 Philipp Christmann , Rishiraj Saha Roy , Gerhard Weikum

Knowledge Base Question Answering (KBQA) challenges models to bridge the gap between natural language and strict knowledge graph schemas by generating executable logical forms. While Large Language Models (LLMs) have advanced this field,…

Computation and Language · Computer Science 2026-01-12 Xin Sun , Zhongqi Chen , Xing Zheng , Qiang Liu , Shu Wu , Bowen Song , Zilei Wang , Weiqiang Wang , Liang Wang

We study the question of when we can provide direct access to the k-th answer to a Conjunctive Query (CQ) according to a specified order over the answers in time logarithmic in the size of the database, following a preprocessing step that…

Databases · Computer Science 2022-11-30 Nofar Carmeli , Nikolaos Tziavelis , Wolfgang Gatterbauer , Benny Kimelfeld , Mirek Riedewald

Interpretability of machine learning (ML) models becomes more relevant with their increasing adoption. In this work, we address the interpretability of ML based question answering (QA) models on a combination of knowledge bases (KB) and…

Computation and Language · Computer Science 2019-06-27 Alona Sydorova , Nina Poerner , Benjamin Roth

Epistemic logic programs (ELPs) are a popular generalization of standard Answer Set Programming (ASP) providing means for reasoning over answer sets within the language. This richer formalism comes at the price of higher computational…

Computational Complexity · Computer Science 2020-01-14 Markus Hecher , Michael Morak , Stefan Woltran

Motivated by the incompleteness of modern knowledge graphs, a new setup for query answering has emerged, where the goal is to predict answers that do not necessarily appear in the knowledge graph, but are present in its completion. In this…

Machine Learning · Computer Science 2026-01-30 Krzysztof Olejniczak , Xingyue Huang , Mikhail Galkin , İsmail İlkan Ceylan

Complex Query Answering (CQA) over Knowledge Graphs (KGs) is a challenging task. Given that KGs are usually incomplete, neural models are proposed to solve CQA by performing multi-hop logical reasoning. However, most of them cannot perform…

Machine Learning · Computer Science 2024-08-13 Chongzhi Zhang , Zhiping Peng , Junhao Zheng , Qianli Ma

Complex Query Answering (CQA) is a challenge task of Knowledge Graph (KG). Due to the incompleteness of KGs, query embedding (QE) methods have been proposed to encode queries and entities into the same embedding space, and treat logical…

Artificial Intelligence · Computer Science 2025-09-30 Yao Xu , Shizhu He , Cunguang Wang , Li Cai , Kang Liu , Jun Zhao

Automated mathematical reasoning is a challenging problem that requires an agent to learn algebraic patterns that contain long-range dependencies. Two particular tasks that test this type of reasoning are (1) mathematical equation…

Machine Learning · Computer Science 2021-04-08 Ankur Mali , Alexander Ororbia , Daniel Kifer , C. Lee Giles

We study the enumeration complexity of Unions of Conjunctive Queries(UCQs). We aim to identify the UCQs that are tractable in the sense that the answer tuples can be enumerated with a linear preprocessing phase and a constant delay between…

Databases · Computer Science 2021-05-07 Nofar Carmeli , Markus Kröll

Neural methods for Complex Query Answering (CQA) over knowledge graphs (KGs) are widely believed to learn patterns that generalize beyond explicit graph structure, allowing them to infer answers that are unreachable through symbolic query…

Artificial Intelligence · Computer Science 2026-05-12 Yannick Brunink , Daniel Daza , Yunjie He , Michael Cochez