scholarly journals Explanations for Inconsistency-Tolerant Query Answering under Existential Rules

2020 ◽  
Vol 34 (03) ◽  
pp. 2909-2916
Author(s):  
Thomas Lukasiewicz ◽  
Enrico Malizia ◽  
Cristian Molinaro
Keyword(s):  
Knowledge Base ◽  
Complexity Analysis ◽  
Knowledge Bases ◽  
Query Answering ◽  
Complexity Measures ◽  
Rule Languages ◽  
Wide Range ◽  
Inconsistent Knowledge

Querying inconsistent knowledge bases is a problem that has attracted a great deal of interest over the last decades. While several semantics of query answering have been proposed, and their complexity is rather well-understood, little attention has been paid to the problem of explaining query answers. Explainability has recently become a prominent problem in different areas of AI. In particular, explaining query answers allows users to understand not only what is entailed by an inconsistent knowledge base, but also why. In this paper, we address the problem of explaining query answers for existential rules under three popular inconsistency-tolerant semantics, namely, the ABox repair, the intersection of repairs, and the intersection of closed repairs semantics. We provide a thorough complexity analysis for a wide range of existential rule languages and for different complexity measures.

scholarly journals Explanations for Negative Query Answers under Existential Rules

2020 ◽  
Author(s):  
İsmail İlkan Ceylan ◽  
Thomas Lukasiewicz ◽  
Enrico Malizia ◽  
Cristian Molinaro ◽  
Andrius Vaicenavičius
Keyword(s):  
Knowledge Representation ◽  
Conceptual Knowledge ◽  
Complexity Analysis ◽  
Description Logics ◽  
Query Answering ◽  
Data Sources ◽  
Complexity Measures ◽  
Rule Languages ◽  
Wide Range ◽  
Ontology Languages

Ontology-mediated query answering is an extensively studied paradigm, where the conceptual knowledge provided by an ontology is leveraged towards more enhanced querying of data sources. A major advantage of ontological reasoning is its interpretability, which allows one to derive explanations for query answers. Indeed, explanations have a long history in knowledge representation, and have also been investigated for ontology languages based on description logics and existential rules. Existing works on existential rules, however, merely focus on understanding why a query is entailed, i.e., explaining positive query answers. In this paper, we continue this line of research and address another important problem, namely, explaining why a query is not entailed under existential rules, i.e., explaining negative query answers. We consider various problems related to explaining non-entailments from the abduction literature, and also introduce new problems. For all considered problems, we give a detailed complexity analysis for a wide range of existential rule languages and complexity measures.

scholarly journals Complexity of Approximate Query Answering under Inconsistency in Datalog+/-

2018 ◽  
Author(s):  
Thomas Lukasiewicz ◽  
Enrico Malizia ◽  
Cristian Molinaro
Keyword(s):  
Knowledge Base ◽  
Standard Setting ◽  
Knowledge Bases ◽  
Query Answering ◽  
Conjunctive Query ◽  
Approximate Query Answering ◽  
Wide Range ◽  
Approximate Query

Several semantics have been proposed to query inconsistent ontological knowledge bases, including the intersection of repairs and the intersection of closed repairs as two approximate inconsistency-tolerant semantics. In this paper, we analyze the complexity of conjunctive query answering under these two semantics for a wide range of Datalog+/- languages. We consider both the standard setting, where errors may only be in the database, and the generalized setting, where also the rules of a Datalog+/- knowledge base may be erroneous.

Preference-based Inconsistency-Tolerant Query Answering under Existential Rules

2020 ◽  
Author(s):  
Marco Calautti ◽  
Sergio Greco ◽  
Cristian Molinaro ◽  
Irina Trubitsyna
Keyword(s):  
Knowledge Bases ◽  
User Preferences ◽  
Query Answering ◽  
Rule Languages ◽  
Inconsistent Knowledge ◽  
Consistent Subset

Query answering over inconsistent knowledge bases is a problem that has attracted a great deal of interest over the years. Different inconsistency-tolerant semantics have been proposed, and most of them are based on the notion of repair, that is, a "maximal" consistent subset of the database. In general, there can be several repairs, so it is often natural and desirable to express preferences among them. In this paper, we propose a framework for querying inconsistent knowledge bases under user preferences for existential rule languages. We provide generalizations of popular inconsistency-tolerant semantics taking preferences into account and study the data and combined complexity of different relevant problems.

scholarly journals Computing Approximate Query Answers over Inconsistent Knowledge Bases

2018 ◽  
Author(s):  
Sergio Greco ◽  
Cristian Molinaro ◽  
Irina Trubitsyna
Keyword(s):  
Knowledge Base ◽  
Knowledge Bases ◽  
Query Answering ◽  
Compact Representation ◽  
Fine Grained ◽  
Polynomial Time Approximation Algorithm ◽  
Consistent Query Answering ◽  
Approximate Query ◽  
Inconsistent Knowledge ◽  
Consistent Query Answers

Consistent query answering is a principled approach for querying inconsistent knowledge bases. It relies on the notion of a "repair", that is, a maximal consistent subset of the facts in the knowledge base. One drawback of this approach is that entire facts are deleted to resolve inconsistency, even if they may still contain useful "reliable" information. To overcome this limitation, we propose a new notion of repair allowing values within facts to be updated for restoring consistency. This more fine-grained repair primitive allows us to preserve more information in the knowledge base. We also introduce the notion of a "universal repair", which is a compact representation of all repairs. Then, we show that consistent query answering in our framework is intractable (coNP-complete). In light of this result, we develop a polynomial time approximation algorithm for computing a sound (but possibly incomplete) set of consistent query answers.

scholarly journals The Application of Complexity Analysis in Brain Blood-Oxygen Signal

2021 ◽  
Vol 11 (11) ◽  
pp. 1415
Author(s):  
Xiaoyang Xin ◽  
Shuyang Long ◽  
Mengdan Sun ◽  
Xiaoqing Gao
Keyword(s):  
Complexity Analysis ◽  
Spatial Scales ◽  
Blood Oxygen ◽  
Complexity Measures ◽  
Future Directions ◽  
Brain Physiology ◽  
Wide Range ◽  
Signal Complexity ◽  
Temporal And Spatial ◽  
The Brain

One of the daunting features of the brain is its physiology complexity, which arises from the interaction of numerous neuronal circuits that operate over a wide range of temporal and spatial scales, enabling the brain to adapt to the constantly changing environment and to perform various cognitive functions. As a reflection of the complexity of brain physiology, the complexity of brain blood-oxygen signal has been frequently studied in recent years. This paper reviews previous literature regarding the following three aspects: (1) whether the complexity of the brain blood-oxygen signal can serve as a reliable biomarker for distinguishing different patient populations; (2) which is the best algorithm for complexity measure? And (3) how to select the optimal parameters for complexity measures. We then discuss future directions for blood-oxygen signal complexity analysis, including improving complexity measurement based on the characteristics of both spatial patterns of brain blood-oxygen signal and latency of complexity itself. In conclusion, the current review helps to better understand complexity analysis in brain blood-oxygen signal analysis and provide useful information for future studies.

Analyzing the linguistic complexity of German learner language in a reading comprehension task

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Zarah Weiss ◽  
Detmar Meurers
Keyword(s):  
Reading Comprehension ◽  
Language Proficiency ◽  
Complexity Analysis ◽  
College Level ◽  
Complexity Measures ◽  
Linguistic Complexity ◽  
Foreign Language Learners ◽  
Wide Range ◽  
Linguistic Methods ◽  
Learner Language

Abstract While traditionally linguistic complexity analysis of learner language is mostly based on essays, there is increasing interest in other task types. This is crucial for obtaining a broader empirical basis for characterizing language proficiency and highlights the need to advance our understanding of how task and learner properties interact in shaping the linguistic complexity of learner productions. It also makes it important to determine which complexity measures generalize well across which tasks. In this paper, we investigate the linguistic complexity of answers to reading comprehension questions written by foreign language learners of German at the college level. Analyzing the corpus with computational linguistic methods identifying a wide range of complexity features, we explore which linguistic complexity analyses can successfully be performed for such short answers, how learner proficiency impacts the results, how generalizable they are across different contexts, and how the quality of the underlying analysis impacts the results.

scholarly journals Complexity of Inconsistency-Tolerant Query Answering in Datalog+/– under Cardinality-Based Repairs

2019 ◽  
Vol 33 ◽  
pp. 2962-2969 ◽  
Author(s):  
Thomas Lukasiewicz ◽  
Enrico Malizia ◽  
Andrius Vaicenavičius
Keyword(s):  
Computational Complexity ◽  
Knowledge Bases ◽  
Query Answering ◽  
Conjunctive Query ◽  
Wide Range ◽  
Consistent Subset

Querying inconsistent ontological knowledge bases is an important problem in practice, for which several inconsistencytolerant query answering semantics have been proposed, including query answering relative to all repairs, relative to the intersection of repairs, and relative to the intersection of closed repairs. In these semantics, one assumes that the input database is erroneous, and the notion of repair describes a maximally consistent subset of the input database, where different notions of maximality (such as subset and cardinality maximality) are considered. In this paper, we give a precise picture of the computational complexity of inconsistencytolerant (Boolean conjunctive) query answering in a wide range of Datalog± languages under the cardinality-based versions of the above three repair semantics.

scholarly journals Reverse Engineering Queries in Ontology-Enriched Systems: The Case of Expressive Horn Description Logic Ontologies

2018 ◽  
Author(s):  
Víctor Gutiérrez-Basulto ◽  
Jean Christoph Jung ◽  
Leif Sabellek
Keyword(s):  
Reverse Engineering ◽  
Knowledge Base ◽  
Description Logic ◽  
Knowledge Bases ◽  
Query Answering ◽  
Conjunctive Queries ◽  
Complexity Bounds ◽  
Query By Example

We introduce the query-by-example (QBE) paradigm for query answering in the presence of ontologies. Intuitively, QBE permits non-expert users to explore the data by providing examples of the information they (do not) want, which the system then generalizes into a query. Formally, we study the following question: given a knowledge base and sets of positive and negative examples, is there a query that returns all positive but none of the negative examples?  We focus on description logic knowledge bases with ontologies formulated in Horn-ALCI and (unions of) conjunctive queries. Our main contributions are characterizations, algorithms and tight complexity bounds for QBE.  

scholarly journals Formation of a Knowledge base in the Field of Patenting Technologies and Equipment for Involvement in the Processing and use of Woody Greenery in Industry, Agriculture and in the Social Sphere

2020 ◽  
Vol 8 (4) ◽  
pp. 1400-1407
Keyword(s):  
Knowledge Base ◽  
Raw Materials ◽  
Biological Effects ◽  
Knowledge Bases ◽  
Intellectual Activity ◽  
Important Place ◽  
Social Sphere ◽  
The Social ◽  
Wide Range ◽  
Technical Solutions

In recent years, the results of intellectual activity - numerous technological and technical solutions - have been patented for the basic operations of the forestry complex. Insufficient attention is paid to the formation of knowledge bases in the field of technologies and equipment for involving non-timber forest resources in the processing. The formation of databases in this area is caused by the identified trends in the development of products from various types of natural raw materials for the pharmaceutical, food, cosmetic industries and other spheres of the social sphere and the economy. Among the types of natural raw materials, an important place is occupied by raw materials with a wide range of biological effects, including woody greens. The development of a knowledge base in the field of involving tree greenery in various spheres of the social sphere and economy was carried out on the basis of a systematic patent search. The analysis made it possible to form a knowledge base about the main most characteristic technological and technical solutions patented in Russia in the field of harvesting, processing and use of greenery of tree species growing in Russia in industry, agriculture and in the social sphere. These solutions are classified according to the types of greenery used (complex of conifers, and in the context of woody greenery of fir, pine, larch, cedar and dwarf cedar, juniper, and deciduous trees). Within each class of patents in the field of wood greenery processing, patents are given taking into account the directions of their use, the effects achieved as a result of the implementation of patented solutions with the allocation of economic entities conducting patenting in the studied area. In this regard, the authors carried out research with the conduct of patent information search, collection and systematization of information. The state and tendencies of directions of patenting in the field of technologies and equipment for the use of tree greenery in industry and in the social sphere are revealed, the main goals of patenting (effects) are determined to achieve which the patented intellectual property objects are considered. The most interesting patents collected during the formation of the knowledge base are presented.

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