1,720,961 research outputs found
On reasoning about action and change in the fluent calculus
No full textWe investigate the possibilities for automatic reasoning about action and change in the Fluent Calculus. To this end, by relating reasoning about action and change in the Fluent Calculus to model checking of dynamic systems, we pursue a systematic approach to analysing Fluent Calculus domains. Motivated by the different properties of Fluent Calculus domains known from the literature we define several Fluent Calculus fragments by syntactic criteria. We distinguish classes of dynamic properties to be inferred, focusing on several versions of planning problems. To apply results concerning the decidability of model checking of dynamic systems to decidability of reasoning about Fluent Calculus domains we establish tight relationships between models of the previously defined Fluent Calculus fragments and well known computational models like finite automata, Petri nets and two-counter machines. Furthermore, we show that dynamic properties, for example the existence of a plan, can be characterised by formulas of modal/temporal logics. Then, for every Fluent Calculus fragment and every class of dynamic properties we investigate the existence of a decision procedure. The results about decidability of all considered planning problems for the Fluent Calculus fragment FCPL is particularly interesting. In FCPL domains we can only use constant fluent and action symbols and the executability of actions must not depend on negative preconditions. Despite these restrictions, FCPL allows the specification of systems with an infinite state space. With the help of our decidability results we develop a partial deduction algorithm to solve conjunctive planning problems for some Fluent Calculus domains. Our algorithm is the first complete reasoning method which can automatically solve conjunctive planning problems for FCPL domains.</p
Generating inductive verification proofs for Isabelle using the partial evaluator Ecce
No full textEcce is a partial deduction system which can be used to automatically generate abstractions for the model checking of many infinite state systems. We show that to verify the abstractions generated by Ecce we may employ the proof assistant Isabelle. Thereby Ecce is used to generate the specification, hypotheses and proof script in Isabelle's theory format. Then, in many cases, Isabelle can automatically execute these proof scripts and thereby verify the soundness of Ecce's abstraction. In this work we focus on the specification and verification of Petri nets
Inductive theorem proving by program specialisation: Generating proofs for Isabelle using Ecce (Invited talk)
No full textIn this paper we discuss the similarities between program specialisation and inductive theorem proving, and then show how program specialisation can be used to perform inductive theorem proving. We then study this relationship in more detail for a particular class of problems (verifying infinite state Petri nets) in order to establish a clear link between program specialisation and inductive theorem proving. In particular, we use the program specialiser Ecce to generate specifications, hypotheses and proof scripts in the theory format of the proof assistant Isabelle. Then, in many cases, Isabelle can automatically execute these proof scripts and thereby verify the soundness of Ecce's verification process and of the correspondence between program specialisation and inductive theorem proving
Solving Coverability Problems of Petri Nets by Partial Deduction
No full textIn recent work it has been shown that infinite state model checking can be performed by a combination of partial deduction of logic programs and abstract interpretation. This paper focuses on one particular class of problem--coverability for (infinite state) Petri nets--and shows how existing techniques and tools for declarative programs can be successfully applied. In particular, we show that a restricted form of partial deduction is already powerful enough to decide all coverability properties of Petri Nets. We also prove that two particular instances of partial deduction exactly compute the Karp-Miller tree as well as Finkel's minimal coverability set. We thus establish an interesting link between algorithms for Petri nets and logic program specialisation
Coverability of Reset Petri Nets and other Well-Structured Transition Systems by Partial Deduction
No full textIn recent work it has been shown that infinite state model checking can be performed by a combination of partial deduction of logic programs and abstract interpretation. It has also been shown that partial deduction is powerful enough to mimic certain algorithms to decide coverability properties of Petri nets. These algorithms are forward algorithms and hard to scale up to deal with more complicated systems. Recently, it has been proposed to use a backward algorithm scheme instead. This scheme is applicable to so--called well--structured transition systems and was successfully used, e.g., to solve coverability problems for reset Petri nets. In this paper, we discuss how partial deduction can mimic many of these backward algorithms as well. We prove this link in particular for reset Petri nets and Petri nets with transfer and doubling arcs. We thus establish a surprising link between algorithms in Petri net theory and program specialisation, and also shed light on the power of using logic program specialisation for infinite state model checking
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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