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19
Legislation as logic programs
- In Logic Programming in Action
, 1992
"... The driving force behind logic programming is the idea that a single formalism suffices for both logic and computation, and that logic subsumes computation. But logic, as this series of volumes proves, is a broad church, with many denomi-nations and communities, coexisting in varying degrees of harm ..."
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Cited by 40 (2 self)
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The driving force behind logic programming is the idea that a single formalism suffices for both logic and computation, and that logic subsumes computation. But logic, as this series of volumes proves, is a broad church, with many denomi-nations and communities, coexisting in varying degrees of harmony. Computing is,
OpenRuleBench: An analysis of the performance of rule engines
- In WWW: Semantic Data Track
, 2009
"... The Semantic Web initiative has led to an upsurge of the interest in rules as a general and powerful way of processing, combining, and analyzing semantic information. Since several of the technologies underlying rule-based systems are already quite mature, it is important to understand how such syst ..."
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Cited by 29 (0 self)
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The Semantic Web initiative has led to an upsurge of the interest in rules as a general and powerful way of processing, combining, and analyzing semantic information. Since several of the technologies underlying rule-based systems are already quite mature, it is important to understand how such systems might perform on the Web scale. OpenRuleBench is a suite of benchmarks for analyzing the performance and scalability of different rule engines. Currently the study spans five different technologies and eleven systems, but OpenRuleBench is an open community resource, and contributions from the community are welcome. In this paper, we describe the tested systems and technologies, the methodology used in testing, and analyze the results.
Towards formal foundations of event queries and rules
- In Proc. Int. Workshop on Event-Driven Architecture, Processing and Systems
, 2007
"... The field of complex event processing still lacks formal foundations. In particular, event queries require both declarative and operational semantics. We put forward for discussion a proposal towards formal foundations of event queries that aims at making well-known results from database queries app ..."
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Cited by 10 (4 self)
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The field of complex event processing still lacks formal foundations. In particular, event queries require both declarative and operational semantics. We put forward for discussion a proposal towards formal foundations of event queries that aims at making well-known results from database queries applicable to event queries. Declarative semantics of event queries and rules are given as a model theory with accompanying fixpoint theory. Operational semantics are then obtained by translating the considered queries into relational algebra expressions. We show the suitability of relational algebra for the kind of incremental evaluation usually required for event queries. With the aim of generating further discussion of formal foundations in the research community, we reflect openly upon both strengths and weaknesses of the presented approach. 1.
Complete query answering over horn ontologies using a triple store
- IN: PROC. OF THE 12TH INTERNATIONAL SEMANTIC WEB CONFERENCE (ISWC), SPRINGER LNCS (2013
"... In our previous work, we showed how a scalable OWL 2 RL reasoner can be used to compute both lower and upper bound query an-swers over very large datasets and arbitrary OWL 2 ontologies. However, when these bounds do not coincide, there still remain a number of possi-ble answer tuples whose status ..."
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Cited by 10 (4 self)
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In our previous work, we showed how a scalable OWL 2 RL reasoner can be used to compute both lower and upper bound query an-swers over very large datasets and arbitrary OWL 2 ontologies. However, when these bounds do not coincide, there still remain a number of possi-ble answer tuples whose status is not determined. In this paper, we show how in the case of Horn ontologies one can exploit the lower and upper bounds computed by the RL reasoner to efficiently identify a subset of the data and ontology that is large enough to resolve the status of these tuples, yet small enough so that the status can be computed using a fully-fledged OWL 2 reasoner. The resulting hybrid approach has enabled us to compute exact answers to queries over datasets and ontologies where previously only approximate query answering was possible.
Two Semantics for CEP, no Double Talk: Complex Event Relational Algebra (CERA) and its Application to XChange^EQ
, 2010
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Four Lessons in Versatility or How Query Languages Adapt to the Web
"... Exposing not only human-centered information, but machine-processable data on the Web is one of the commonalities of recent Web trends. It has enabled a new kind of applications and businesses where the data is used in ways not foreseen by the data providers. Yet this exposition has fractured the W ..."
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Cited by 4 (4 self)
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Exposing not only human-centered information, but machine-processable data on the Web is one of the commonalities of recent Web trends. It has enabled a new kind of applications and businesses where the data is used in ways not foreseen by the data providers. Yet this exposition has fractured the Web into islands of data, each in different Web formats: Some providers choose XML, others RDF, again others JSON or OWL, for their data, even in similar domains. This fracturing stifles innovation as application builders have to cope not only with one Web stack (e.g., XML technology) but with several ones, each of considerable complexity. With Xcerpt we have developed a rule- and pattern based query language that aims to give shield application builders from much of this complexity: In a single query language XML and RDF data can be accessed, processed, combined, and re-published. Though the need for combined access to XML and RDF data has been recognized in previous work (including the W3C’s GRDDL), our approach differs in four main aspects: (1) We provide a single language (rather than two separate or embedded languages), thus minimizing the conceptual overhead of dealing with disparate data formats. (2) Both the declarative (logic-based) and the operational semantics are unified in that they apply for querying XML and RDF in the same way. (3) We show that the resulting query language can be implemented reusing traditional database technology, if desirable. Nevertheless, we also give a unified evaluation approach based on interval labelings of graphs that is at least as fast as existing approaches for tree-shaped XML data, yet provides linear time and space querying also for many RDF graphs. We believe that Web query languages are the right tool for declarative data access in Web applications and that Xcerpt is a significant step towards a more convenient, yet highly efficient data access in a “Web of Data”.
Reasoning as Axioms Change Incremental View Maintenance Reconsidered
"... Abstract. We present a novel incremental algorithm to compute changes to materialized views in logic databases like those used by rule-based reasoners. Such reasoners have to address the problem of changing axioms in the presence of materializations of derived atoms. Existing approaches have drawbac ..."
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Abstract. We present a novel incremental algorithm to compute changes to materialized views in logic databases like those used by rule-based reasoners. Such reasoners have to address the problem of changing axioms in the presence of materializations of derived atoms. Existing approaches have drawbacks: some require to generate and evaluate large transformed programs that are in Datalog ¬ while the source program is in Datalog and significantly smaller; some recompute the whole extension of a predicate even if only a small part of this extension is affected by the change. The method presented in this article overcomes both drawbacks, arguably at an acceptable price: a slight adaptation of the semi-naïve forward chaining. 1
Organic Synthesis as Artificial Intelligence Planning
"... Abstract. We explore advantages that can be gained from using expressive logic languages for semantic modelling of chemical reactions. First, we present a novel approach for logical representation of notions in organic chemistry, as well as for reasoning about generic chemical reactions. Subsequentl ..."
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Abstract. We explore advantages that can be gained from using expressive logic languages for semantic modelling of chemical reactions. First, we present a novel approach for logical representation of notions in organic chemistry, as well as for reasoning about generic chemical reactions. Subsequently, using this new semantic modeling of reactions, we explore what reasoning problems can be solved. We focus on solving organic chemistry synthesis problems, where the goal is to synthesize the target molecule from a set of starting stage molecules. We argue that this problem can be reduced to a planning problem in Artificial Intelligence. We conduct experimental study including empirical assessment of a PROLOG planner and two state-of-the-art planners. We investigate if they are capable of solving a set of instances of the organic synthesis problem. We report numerical data from our study and do comparative analysis of the planners. The novelty of our work is in using state-of-the art planners for solving the organic synthesis problem. The significance of our work is in methodology that we developed and in showing that expressive logical language can be useful for semantic modeling.
Subsumption-Based Resolution for Rule Languages with Rich Unification
"... Finding, transforming or integrating information on the Web and Semantic Web often involves matching a structured query with semi-structured data. In logic programming languages, this notion of matching is formalized by unification. With the plethora of different data formats available on the Web, t ..."
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Finding, transforming or integrating information on the Web and Semantic Web often involves matching a structured query with semi-structured data. In logic programming languages, this notion of matching is formalized by unification. With the plethora of different data formats available on the Web, there is no single sensible notion of matching or unifying queries with data. We introduce the notion of rich unification, which generalizes standard unification in logic programming, matching SPARQL query patterns with RDF graphs, evaluation of XPath or XQuery expressions on XML documents, and simulation of Xcerpt terms with RDF or XML data. On top of rich unification, we introduce a rule language Xcerpts with recursion and negation as failure which is a variant of Xcerpt. We present an evaluation algorithm, called Subsumption-Based Resolution for rule languages with rich unification (SBR) resolving a query w.r.t. a locally stratified program with the bounded-term-size property. With the help of numerous Xcerpts resolution examples we explain the main features of the algorithm and its differences to some other evaluation strategies such as SLD-, OLDT- and
