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An Algebraic Presentation of Term Graphs, via GSMonoidal Categories
 Applied Categorical Structures
, 1999
"... . We present a categorical characterisation of term graphs (i.e., finite, directed acyclic graphs labeled over a signature) that parallels the wellknown characterisation of terms as arrows of the algebraic theory of a given signature (i.e., the free Cartesian category generated by it). In particula ..."
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Cited by 37 (24 self)
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. We present a categorical characterisation of term graphs (i.e., finite, directed acyclic graphs labeled over a signature) that parallels the wellknown characterisation of terms as arrows of the algebraic theory of a given signature (i.e., the free Cartesian category generated by it). In particular, we show that term graphs over a signature \Sigma are onetoone with the arrows of the free gsmonoidal category generated by \Sigma. Such a category satisfies all the axioms for Cartesian categories but for the naturality of two transformations (the discharger ! and the duplicator r), providing in this way an abstract and clear relationship between terms and term graphs. In particular, the absence of the naturality of r and ! has a precise interpretation in terms of explicit sharing and of loss of implicit garbage collection, respectively. Keywords: algebraic theories, directed acyclic graphs, gsmonoidal categories, symmetric monoidal categories, term graphs. Mathematical Subject Clas...
Admissible Graph Rewriting and Narrowing
 IN PROCEEDINGS OF THE JOINT INTERNATIONAL CONFERENCE AND SYMPOSIUM ON LOGIC PROGRAMMING
, 1998
"... We address the problem of graph rewriting and narrowing as the underlying operational semantics of rulebased programming languages. We propose new optimal graph rewriting and narrowing strategies in the setting of orthogonal constructorbased graph rewriting systems. For this purpose, we first char ..."
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Cited by 29 (6 self)
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We address the problem of graph rewriting and narrowing as the underlying operational semantics of rulebased programming languages. We propose new optimal graph rewriting and narrowing strategies in the setting of orthogonal constructorbased graph rewriting systems. For this purpose, we first characterize a subset of graphs, called admissible graphs. A graph is admissible if none of its defined operations belongs to a cycle. We then prove the confluence, as well as the confluence modulo bisimilarity (unraveling), of the admissible graph rewriting relation. Afterwards, we define a sequential graph rewriting strategy by using Antoy’s definitional trees. We show that the resulting strategy computes only needed redexes and develops optimal derivations w.r.t. the number of steps. Finally, we tackle the graph narrowing relation over admissible graphs and propose a sequential narrowing strategy which computes independent solutions and develops shorter derivations than most general graph narrowing.
Lazy rewriting on eager machinery
 ACM Transactions on Programming Languages and Systems
, 2000
"... The article introduces a novel notion of lazy rewriting. By annotating argument positions as lazy, redundant rewrite steps are avoided, and the termination behaviour of a term rewriting system can be improved. Some transformations of rewrite rules enable an implementation using the same primitives a ..."
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Cited by 23 (1 self)
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The article introduces a novel notion of lazy rewriting. By annotating argument positions as lazy, redundant rewrite steps are avoided, and the termination behaviour of a term rewriting system can be improved. Some transformations of rewrite rules enable an implementation using the same primitives as an implementation of eager rewriting. 1
Rational Term Rewriting
, 1998
"... . Rational terms (possibly infinite terms with finitely many subterms) can be represented in a finite way via terms, that is, terms over a signature extended with selfinstantiation operators. For example, f ! = f(f(f(: : :))) can be represented as x :f(x) (or also as x :f(f(x)), f(x :f(x)), ..."
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Cited by 21 (12 self)
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. Rational terms (possibly infinite terms with finitely many subterms) can be represented in a finite way via terms, that is, terms over a signature extended with selfinstantiation operators. For example, f ! = f(f(f(: : :))) can be represented as x :f(x) (or also as x :f(f(x)), f(x :f(x)), . . . ). Now, if we reduce a term t to s via a rewriting rule using standard notions of the theory of Term Rewriting Systems, how are the rational terms corresponding to t and to s related? We answer to this question in a satisfactory way, resorting to the definition of infinite parallel rewriting proposed in [7]. We also provide a simple, algebraic description of term rewriting through a variation of Meseguer's Rewriting Logic formalism. 1 Introduction Rational terms are possibly infinite terms with a finite set of subterms. They show up in a natural way in Theoretical Computer Science whenever some finite cyclic structures are of concern (for example data flow diagrams, cyclic te...
A rewriting calculus for cyclic higherorder term graphs
 in "2nd International Workshop on Term Graph Rewriting  TERMGRAPH’2004
, 2004
"... graphs ..."
On Constructorbased Graph Rewriting Systems
 RESEARCH REPORT 985I, IMAG
, 1997
"... We address the problem of graph rewriting as the underlying operational semantics of rulebased programming languages. We define a new optimal graph rewriting strategy in the setting of orthogonal constructorbased graph rewriting systems. For this purpose, we first characterize a subset of graphs, ..."
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Cited by 16 (3 self)
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We address the problem of graph rewriting as the underlying operational semantics of rulebased programming languages. We define a new optimal graph rewriting strategy in the setting of orthogonal constructorbased graph rewriting systems. For this purpose, we first characterize a subset of graphs, called admissible graphs. A graph is admissible if none of its defined operations belongs to a cycle. We then prove the confluence, as well as the confluence modulo bisimilarity (unraveling), of the admissible graph rewriting relation. Finally, we define a sequential graph rewriting strategy by using Antoy's definitional trees. We show that the resulting strategy computes only needed redexes and develops optimal derivations w.r.t. the number of steps.
Interaction Nets and Term Rewriting Systems
, 1998
"... Term rewriting systems provide a framework in which it is possible to specify and program in a traditional syntax (oriented equations). Interaction nets, on the other hand, provide a graphical syntax for the same purpose, but can be regarded as being closer to an implementation since the reductio ..."
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Cited by 13 (7 self)
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Term rewriting systems provide a framework in which it is possible to specify and program in a traditional syntax (oriented equations). Interaction nets, on the other hand, provide a graphical syntax for the same purpose, but can be regarded as being closer to an implementation since the reduction process is local and asynchronous, and all the operations are made explicit, including discarding and copying of data. Our aim is to bridge the gap between the above formalisms by showing how to understand interaction nets in a term rewriting framework. This allows us to transfer results from one paradigm to the other, deriving syntactical properties of interaction nets from the (wellstudied) properties of term rewriting systems; in particular concerning termination and modularity. Keywords: term rewriting, interaction nets, termination, modularity. 1 Introduction Term rewriting systems provide a general framework for specifying and reasoning about computation. They can be regarde...
Rewriting On Cyclic Structures: Equivalence Between The Operational And The Categorical Description
, 1999
"... . We present a categorical formulation of the rewriting of possibly cyclic term graphs, based on a variation of algebraic 2theories. We show that this presentation is equivalent to the wellaccepted operational definition proposed by Barendregt et aliibut for the case of circular redexes, fo ..."
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Cited by 12 (6 self)
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. We present a categorical formulation of the rewriting of possibly cyclic term graphs, based on a variation of algebraic 2theories. We show that this presentation is equivalent to the wellaccepted operational definition proposed by Barendregt et aliibut for the case of circular redexes, for which we propose (and justify formally) a different treatment. The categorical framework allows us to model in a concise way also automatic garbage collection and rules for sharing/unsharing and folding/unfolding of structures, and to relate term graph rewriting to other rewriting formalisms. R'esum'e. Nous pr'esentons une formulation cat'egorique de la r'e'ecriture des graphes cycliques des termes, bas'ee sur une variante de 2theorie alg'ebrique. Nous prouvons que cette pr'esentation est 'equivalente `a la d'efinition op'erationnelle propos'ee par Barendregt et d'autres auteurs, mais pas dons le cas des radicaux circulaires, pour lesquels nous proposons (et justifions formellem...
From Term Rewriting to Generalised Interaction Nets
, 1996
"... . In this paper we present a system of interaction that generalises Lafont's interaction nets by allowing computation in several nets in parallel and communication through a state. This framework allows us to represent large classes of term rewriting systems, genuine parallel functions, nondetermin ..."
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Cited by 7 (4 self)
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. In this paper we present a system of interaction that generalises Lafont's interaction nets by allowing computation in several nets in parallel and communication through a state. This framework allows us to represent large classes of term rewriting systems, genuine parallel functions, nondeterminism, communication, sharing, and hence can be used to code features from Standard ML and Concurrent ML. 1 Introduction Term rewriting systems can be regarded as a multiparadigm specification language, or as an abstract model of computation (abstract in the sense that they specify actions but not control; they are free from strategies). Lafont's interaction nets are a graphical framework based on net rewriting which is much closer to a real model of computation in that all the operations are made explicit, including discarding and copying of data. Moreover, interaction nets can be regarded as a distributed model of computation since all reductions are local. In a previous paper [2] we began...
Infinitary Rewriting and Cyclic Graphs
 Electronic Notes in Theoretical Computer Science
, 1995
"... Infinitary rewriting allows infinitely large terms and infinitely long reduction sequences. There are two computational motivations for studying these: the infinite data structures implicit in lazy functional programming, and the use of rewriting of possibly cyclic graphs as an implementation techni ..."
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Cited by 4 (0 self)
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Infinitary rewriting allows infinitely large terms and infinitely long reduction sequences. There are two computational motivations for studying these: the infinite data structures implicit in lazy functional programming, and the use of rewriting of possibly cyclic graphs as an implementation technique for functional languages. We survey the fundamental properties of infinitary rewriting in orthogonal term rewrite systems, and its relation to cyclic graph rewriting. 1 Introduction Our interest in term and graph rewriting arises from functional languages and their implementation. Functional programs can be seen as term rewrite systems. 2 Terms can be thought of as trees. Representing these trees as graphs allows repeated subterms to be replaced by multiple pointers to the same subgraph. This optimisation has a dramatic effect when rewrite steps are performed. Whenever a variable appears more than once on the righthand side of a rule, when that rule is applied to a graph multiple poi...