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CeTA - A Tool for Certified Termination Analysis  [PDF]
Christian Sternagel,René Thiemann,Sarah Winkler,Harald Zankl
Computer Science , 2012,
Abstract: Since the first termination competition in 2004 it is of great interest, whether a proof that has been automatically generated by a termination tool, is indeed correct. The increasing number of termination proving techniques as well as the increasing complexity of generated proofs (e.g., combinations of several techniques, exhaustive labelings, tree automata, etc.), make certifying (i.e., checking the correctness of) such proofs more and more tedious for humans. Hence the interest in automated certification of termination proofs. This led to the general approach of using proof assistants (like Coq and Isabelle) for certification. We present the latest developments for IsaFoR/CeTA (version 1.03) which is the certifier CeTA, based on the Isabelle/HOL formalization of rewriting IsaFoR.
cTI: A constraint-based termination inference tool for ISO-Prolog  [PDF]
Fred Mesnard,Roberto Bagnara
Computer Science , 2003,
Abstract: We present cTI, the first system for universal left-termination inference of logic programs. Termination inference generalizes termination analysis and checking. Traditionally, a termination analyzer tries to prove that a given class of queries terminates. This class must be provided to the system, for instance by means of user annotations. Moreover, the analysis must be redone every time the class of queries of interest is updated. Termination inference, in contrast, requires neither user annotations nor recomputation. In this approach, terminating classes for all predicates are inferred at once. We describe the architecture of cTI and report an extensive experimental evaluation of the system covering many classical examples from the logic programming termination literature and several Prolog programs of respectable size and complexity.
Certification extends Termination Techniques  [PDF]
Christian Sternagel,René Thiemann
Computer Science , 2012,
Abstract: There are termination proofs that are produced by termination tools for which certifiers are not powerful enough. However, a similar situation also occurs in the other direction. We have formalized termination techniques in a more general setting as they have been introduced. Hence, we can certify proofs using techniques that no termination tool supports so far. In this paper we shortly present two of these formalizations: Polynomial orders with negative constants and Arctic termination.
Termination Prediction for General Logic Programs  [PDF]
Yi-Dong Shen,Danny De Schreye,Dean Voets
Computer Science , 2009,
Abstract: We present a heuristic framework for attacking the undecidable termination problem of logic programs, as an alternative to current termination/non-termination proof approaches. We introduce an idea of termination prediction, which predicts termination of a logic program in case that neither a termination nor a non-termination proof is applicable. We establish a necessary and sufficient characterization of infinite (generalized) SLDNF-derivations with arbitrary (concrete or moded) queries, and develop an algorithm that predicts termination of general logic programs with arbitrary non-floundering queries. We have implemented a termination prediction tool and obtained quite satisfactory experimental results. Except for five programs which break the experiment time limit, our prediction is 100% correct for all 296 benchmark programs of the Termination Competition 2007, of which eighteen programs cannot be proved by any of the existing state-of-the-art analyzers like AProVE07, NTI, Polytool and TALP.
Automated verification of termination certificates  [PDF]
Frédéric Blanqui,Kim Quyen Ly
Computer Science , 2012,
Abstract: In order to increase user confidence, many automated theorem provers provide certificates that can be independently verified. In this paper, we report on our progress in developing a standalone tool for checking the correctness of certificates for the termination of term rewrite systems, and formally proving its correctness in the proof assistant Coq. To this end, we use the extraction mechanism of Coq and the library on rewriting theory and termination called CoLoR.
On Chase Termination Beyond Stratification  [PDF]
Michael Meier,Michael Schmidt,Georg Lausen
Computer Science , 2009,
Abstract: We study the termination problem of the chase algorithm, a central tool in various database problems such as the constraint implication problem, Conjunctive Query optimization, rewriting queries using views, data exchange, and data integration. The basic idea of the chase is, given a database instance and a set of constraints as input, to fix constraint violations in the database instance. It is well-known that, for an arbitrary set of constraints, the chase does not necessarily terminate (in general, it is even undecidable if it does or not). Addressing this issue, we review the limitations of existing sufficient termination conditions for the chase and develop new techniques that allow us to establish weaker sufficient conditions. In particular, we introduce two novel termination conditions called safety and inductive restriction, and use them to define the so-called T-hierarchy of termination conditions. We then study the interrelations of our termination conditions with previous conditions and the complexity of checking our conditions. This analysis leads to an algorithm that checks membership in a level of the T-hierarchy and accounts for the complexity of termination conditions. As another contribution, we study the problem of data-dependent chase termination and present sufficient termination conditions w.r.t. fixed instances. They might guarantee termination although the chase does not terminate in the general case. As an application of our techniques beyond those already mentioned, we transfer our results into the field of query answering over knowledge bases where the chase on the underlying database may not terminate, making existing algorithms applicable to broader classes of constraints.
Preliminary Notes on Termination and Non-Termination Reasoning  [PDF]
Ton Chanh Le
Computer Science , 2013,
Abstract: In this preliminary note, we will illustrate our ideas on automated mechanisms for termination and non-termination reasoning.
Equilibrium and Termination
Vincent Danos,Nicolas Oury
Electronic Proceedings in Theoretical Computer Science , 2010, DOI: 10.4204/eptcs.26.7
Abstract: We present a reduction of the termination problem for a Turing machine (in the simplified form of the Post correspondence problem) to the problem of determining whether a continuous-time Markov chain presented as a set of Kappa graph-rewriting rules has an equilibrium. It follows that the problem of whether a computable CTMC is dissipative (ie does not have an equilibrium) is undecidable.
The Challenges for Implementing the Nagoya Protocol in a Multi-Level Governance Context: Lessons from the Belgian Case  [PDF]
Brendan Coolsaet,Tom Dedeurwaerdere,John Pitseys
Resources , 2013, DOI: 10.3390/resources2040555
Abstract: The Nagoya Protocol on Access and Benefit-sharing is the latest protocol to the Convention on Biological Diversity (CBD). Its implementation can lead to two fundamentally different processes: a market-oriented self-regulatory approach, which emphasizes the self-regulating capacity of the economic actors involved, or a normative institutionalist approach, which focuses on the norms and formal rules of institutions that not only support and frame, but also shape and constrain the actions of the players acting within them. This paper analyzes the challenges related to the implementation of the Nagoya Protocol in the specific case of Belgium, and evaluates the possibility of moving from a self-regulatory to an institutional approach of implementation, which we argue is necessary to achieve the objectives of the Protocol. This move is analyzed in the specific multi-level governance context characterizing the Nagoya Protocol, which has a natural tendency towards a market-oriented self-regulatory approach.
The Professional Medical Journal , 2009,
Abstract: Objective: To compare the efficacy of vaginal misoprostal with that of sublingual misoprostol in 2nd trimester of pregnancy by comparing the induction-expulsion interval between two groups of patients induced with vaginal and sublingual misoprostol. Study design: Interventional, quasi experimental study. Settings: Obstetrics & Gynaecology Unit 1, Sir Ganga Ram Hospital, Lahore. Duration of study: Thirteen months from October 2006 to November 2007. Subjects and Methods: Sixty women at 12-26 weeks of gestation which were selected for termination of pregnancy were assigned into two groups. Thirty women received sublingual misoprostol and thirty women received vaginal misoprostol. Dosage regimen was tablet Misoprostol 200μg 4 hours apart till expulsion of fetus (maximum 5 doses). Main outcome measures were: 1. Induction-expulsion intervals 2. Maternal side effects 3. Fever 4. Nausea/vomiting 5.Diarrhea. Results: Mean induction-expulsion interval in vaginal group was 11.8±8.3 hours and in the sublingual group was 12.8±8.5 hours. Percentage of complete expulsion was 53.3% in both groups. Cases of failed induction in vaginal group were 10% and in sublingual group were 13.3%. One case ( 3.3%) of fever and two cases (6.6%) of vomiting were observed in sublingual group and one case (3.3%) of vomiting was observed in vaginal group. Conclusion: Both routes appear to be equally efficacious for mid trimester pregnancy termination, without significant side effects.
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