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Ondemand strategy annotations revisited: An improved ondemand evaluation strategy
 THEORETICAL COMPUTER SCIENCE
, 2010
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Extending ContextSensitivity in Term Rewriting
"... We propose a generalized version of contextsensitivity in term rewriting based on the notion of “forbidden patterns”. The basic idea is that a rewrite step should be forbidden if the redex to be contracted has a certain shape and appears in a certain context. This shape and context is expressed thr ..."
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We propose a generalized version of contextsensitivity in term rewriting based on the notion of “forbidden patterns”. The basic idea is that a rewrite step should be forbidden if the redex to be contracted has a certain shape and appears in a certain context. This shape and context is expressed through forbidden patterns. In particular we analyze the relationships among this novel approach and the commonly used notion of contextsensitivity in term rewriting, as well as the feasibility of rewriting with forbidden patterns from a computational point of view. The latter feasibility is characterized by demanding that restricting a rewrite relation yields an improved termination behaviour while still being powerful enough to compute meaningful results. Sufficient criteria for both kinds of properties in certain classes of rewrite systems with forbidden patterns are presented. 1
www.elsevier.com/locate/entcs Termination of Lazy Rewriting Revisited
"... Lazy rewriting is a proper restriction of term rewriting that dynamically restricts the reduction of certain arguments of functions in order to obtain termination. In contrast to contextsensitive rewriting, reductions at such argument positions are not completely forbidden but delayed. Based on the ..."
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Lazy rewriting is a proper restriction of term rewriting that dynamically restricts the reduction of certain arguments of functions in order to obtain termination. In contrast to contextsensitive rewriting, reductions at such argument positions are not completely forbidden but delayed. Based on the observation that the only existing (nontrivial) approach to prove termination of such lazy rewrite systems is flawed, we develop a modified approach for transforming lazy rewrite systems into contextsensitive ones that is sound and complete with respect to termination. First experimental results with this transformation based technique are encouraging. Keywords: term rewriting, lazy rewriting, termination, contextsensitive system
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"... the date of receipt and acceptance should be inserted later Abstract When infinitary rewriting was introduced by Kaplan et. al. [7] at the beginning of the 1990s, its term universe was explained as the metric completion of a metric on finite terms. The motivation for this connection to topology was ..."
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the date of receipt and acceptance should be inserted later Abstract When infinitary rewriting was introduced by Kaplan et. al. [7] at the beginning of the 1990s, its term universe was explained as the metric completion of a metric on finite terms. The motivation for this connection to topology was that it allowed to import other wellstudied notions from metric spaces, in particular the notion of convergence as a replacement for normalisation. This paper generalises the approach by parameterising it with a term metric, and applying the process of metric completion not only to terms but also to operations on and relations between terms. The resulting metatheory is studied, leading to a revised notion of infinitary rewrite system. For these systems a method is devised to prove their convergence. 1
A Survey of Rewriting Strategies in Program Transformation Systems
"... Many systems for program transformation exist that are often specialized for a specific object language and/or kind of transformation. All these systems share many ideas about program transformation and use similar techniques, but are often adhoc in many respects. The ultimate goal is to achieve a ..."
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Many systems for program transformation exist that are often specialized for a specific object language and/or kind of transformation. All these systems share many ideas about program transformation and use similar techniques, but are often adhoc in many respects. The ultimate goal is to achieve a specification language or family of specification languages for the highlevel, declarative specification of program transformation systems in which generic, language independent schemas of transformation can be captured, and which admits efficient implementation of those transformations that can scale up to large programs.
Research Report UDMI/18/2002/RR, pages 35–43 Demandness in Rewriting and Narrowing
"... Abstract. The traditional investigation of rewriting and narrowing strategies aims at establishing fundamental properties, such as soundness, completeness and/or optimality, of a strategy. In this work, we analyze and compare rewriting and narrowing strategies from the point of view of the informati ..."
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Abstract. The traditional investigation of rewriting and narrowing strategies aims at establishing fundamental properties, such as soundness, completeness and/or optimality, of a strategy. In this work, we analyze and compare rewriting and narrowing strategies from the point of view of the information taken into account by a strategy to compute a step. The notion of demandness provides a suitable framework for presenting and comparing wellknown strategies. We find the existence of an almost linear sequence of strategies that take into account more and more information. We show on examples that, as we progress on this sequence, a strategy becomes more focused and avoids some useless steps computed by strategies preceding it in this sequence. Our work, which is still in progress, clarifies the behavior of similar or related strategies and it promises to simplify the transfer of some results from one strategy to another. It also suggests that the notion of demandness is both atomic and fundamental to the study of strategies. 1
OnDemand Strategy Annotations Revisited
, 2003
"... In functional languages such as OBJ*, CafeOBJ, and Maude, symbols are given strategy annotations that specify (the order in) which subterms are evaluated. Syntactically, strategy annotations are given either as lists of natural numbers or as lists of integers associated to function symbols whose ..."
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In functional languages such as OBJ*, CafeOBJ, and Maude, symbols are given strategy annotations that specify (the order in) which subterms are evaluated. Syntactically, strategy annotations are given either as lists of natural numbers or as lists of integers associated to function symbols whose (absolute) values refer to the arguments of the corresponding symbol.
An Account of Implementing Applicative Term Rewriting
"... Generation of labelled transition systems from system specifications is highly dependent on efficient rewriting (or related techniques). We give an account of the implementation of two rewriters of the mCRL2 toolset. These rewriters work on open terms and use nonlinear match trees. A comparison is m ..."
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Generation of labelled transition systems from system specifications is highly dependent on efficient rewriting (or related techniques). We give an account of the implementation of two rewriters of the mCRL2 toolset. These rewriters work on open terms and use nonlinear match trees. A comparison is made with other commonly used efficient rewriters.
Compilation of LeftLinear Rewrite Systems via Minimal Rewrite Systems
, 1997
"... and their applications. SMC is sponsored by the Netherlands Organization for Scientific Research (NWO). CWI is a member of ..."
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and their applications. SMC is sponsored by the Netherlands Organization for Scientific Research (NWO). CWI is a member of