4,501 research outputs found
Modelling Garbage Collection Algorithms --- Extend abstract
We show how abstract requirements of garbage collection can be captured using temporal logic. The temporal logic specification can then be used as a basis for process algebra specifications which can involve varying amounts of parallelism. We present two simple CCS specifications as an example, followed by a more complex specification of the cyclic reference counting algorithm. The verification of such algorithms is then briefly discussed
An Abstract Tableau Calculus for the Description Logic SHOI Using UnrestrictedBlocking and Rewriting
Abstract This paper presents an abstract tableau calculus for the description logic SHOI. SHOI is the extension of ALC with singleton concepts, role inverse, transitive roles and role inclusion axioms. The presented tableau calculus is inspired by a recently introduced tableau synthesis framework. Termination is achieved by a variation of the unrestricted blocking mechanism that immediately rewrites terms with respect to the conjectured equalities. This approach leads to reduced search space for decision procedures based on the calculus. We also discuss restrictions of the application of the blocking rule by means of additional side conditions and/or additional premises.
Reasoning with Individuals for the Description Logic SHIQ
While there has been a great deal of work on the development of reasoning
algorithms for expressive description logics, in most cases only Tbox reasoning
is considered. In this paper we present an algorithm for combined Tbox and Abox
reasoning in the SHIQ description logic. This algorithm is of particular
interest as it can be used to decide the problem of (database) conjunctive
query containment w.r.t. a schema. Moreover, the realisation of an efficient
implementation should be relatively straightforward as it can be based on an
existing highly optimised implementation of the Tbox algorithm in the FaCT
system.Comment: To appear at CADE-1
RORS: Enhanced Rule-based OWL Reasoning on Spark
The rule-based OWL reasoning is to compute the deductive closure of an
ontology by applying RDF/RDFS and OWL entailment rules. The performance of the
rule-based OWL reasoning is often sensitive to the rule execution order. In
this paper, we present an approach to enhancing the performance of the
rule-based OWL reasoning on Spark based on a locally optimal executable
strategy. Firstly, we divide all rules (27 in total) into four main classes,
namely, SPO rules (5 rules), type rules (7 rules), sameAs rules (7 rules), and
schema rules (8 rules) since, as we investigated, those triples corresponding
to the first three classes of rules are overwhelming (e.g., over 99% in the
LUBM dataset) in our practical world. Secondly, based on the interdependence
among those entailment rules in each class, we pick out an optimal rule
executable order of each class and then combine them into a new rule execution
order of all rules. Finally, we implement the new rule execution order on Spark
in a prototype called RORS. The experimental results show that the running time
of RORS is improved by about 30% as compared to Kim & Park's algorithm (2015)
using the LUBM200 (27.6 million triples).Comment: 12 page
Transitive closure algorithm MEMTC and its performance analysis
AbstractIn this paper, we present a new algorithm for computing the full transitive closure designed for operation in layered memories. The algorithm is based on strongly connected component detection and on a very compact representation of data. We analyze the average-case performance of the algorithm experimentally in an environment where two layers of memory of different speed are used. In our analysis, we use trace-based simulation of memory operations
Automated Synthesis of Tableau Calculi
This paper presents a method for synthesising sound and complete tableau
calculi. Given a specification of the formal semantics of a logic, the method
generates a set of tableau inference rules that can then be used to reason
within the logic. The method guarantees that the generated rules form a
calculus which is sound and constructively complete. If the logic can be shown
to admit finite filtration with respect to a well-defined first-order semantics
then adding a general blocking mechanism provides a terminating tableau
calculus. The process of generating tableau rules can be completely automated
and produces, together with the blocking mechanism, an automated procedure for
generating tableau decision procedures. For illustration we show the
workability of the approach for a description logic with transitive roles and
propositional intuitionistic logic.Comment: 32 page
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