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Building Equational Proving Tools by Reflection in Rewriting Logic
 In Cafe: An IndustrialStrength Algebraic Formal Method
, 1998
"... This paper explains the design and use of two equational proving tools, namely an inductive theorem prover  to prove theorems about equational specifications with an initial algebra semantics  and a ChurchRosser checkerto check whether such specifications satisfy the ChurchRosser property. ..."
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Cited by 38 (19 self)
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This paper explains the design and use of two equational proving tools, namely an inductive theorem prover  to prove theorems about equational specifications with an initial algebra semantics  and a ChurchRosser checkerto check whether such specifications satisfy the ChurchRosser property. These tools can be used to prove properties of ordersorted equational specifications in Cafe [11] and of membership equational logic specifications in Maude [7, 6]. The tools have been written entirely in Maude and are in fact executable specifications in rewriting logic of the formal inference systems that they implement.
Abstract saturationbased inference
 IN PROCEEDINGS OF THE 18TH ANNUAL SYMPOSIUM ON LOGIC IN COMPUTER SCIENCE
, 2003
"... Solving goals—like deciding word problems or resolving constraints—is much easier in some theory presentations than in others. What have been called “completion processes”, in particular in the study of equational logic, involve finding appropriate presentations of a given theory to solve easily a g ..."
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Cited by 12 (5 self)
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Solving goals—like deciding word problems or resolving constraints—is much easier in some theory presentations than in others. What have been called “completion processes”, in particular in the study of equational logic, involve finding appropriate presentations of a given theory to solve easily a given class of problems. We provide a general prooftheoretic setting within which completionlike processes can be modelled and studied. This framework centers around wellfounded orderings of proofs. It allows for abstract definitions and very general characterizations of saturation processes and redundancy criteria.
DynamicallyTyped Computations for OrderSorted Equational Presentations (Extended Abstract)
 Proc. 21st International Colloquium on Automata, Languages, and Programming, volume 820 of Lecture Notes in Computer Science
, 1994
"... Equational presentations with ordered sorts encompass partially defined functions and subtyping information in an algebraic framework. In this work we address the problem of computing in ordersorted algebras, with very few restrictions on the allowed presentations. We adopt an algebraic framework w ..."
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Cited by 10 (8 self)
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Equational presentations with ordered sorts encompass partially defined functions and subtyping information in an algebraic framework. In this work we address the problem of computing in ordersorted algebras, with very few restrictions on the allowed presentations. We adopt an algebraic framework where equational, membership and existence formulas can be expressed. A complete deduction calculus is provided to incorporate the interaction between all these formulas. The notion of decorated terms is proposed to memorize local sort information, dynamically changed by a rewriting process. A completion procedure for equational presentations with ordered sorts computes a set of rewrite rules with which not only equational theorems of the form (t = t 0 ), but also typing theorems of the for...
Termination Checker and KnuthBendix Completion Tools for Maude Equational Specifications
, 2000
"... This document explains the design and use of a termination checker tool and of a KnuthBendix completion tool. The termination checker tool checks whether an equational specication terminates, and the KnuthBendix completion tool tries to complete an equational speci cation. These tools can be used ..."
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Cited by 8 (1 self)
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This document explains the design and use of a termination checker tool and of a KnuthBendix completion tool. The termination checker tool checks whether an equational specication terminates, and the KnuthBendix completion tool tries to complete an equational speci cation. These tools can be used to prove the termination or to complete ordersorted equational specications in Maude [7, 6, 4]. The tools have been written entirely in Maude and are in fact executable specications in rewriting logic [17] of the formal inference system that they implement. The fact that rewriting logic is reective [8, 3], and that Maude eciently supports reective rewriting logic computations [5, 4] is systematically exploited in the design of the tools. Contents 1
Constraint Solving by Narrowing in Combined Algebraic Domains
 Proc. 11th International Conference on Logic Programming
, 1994
"... Narrowing is a way to integrate function evaluation and equality definition into logic programming. Here we show how this can be combined with the constraint paradigm. We propose a solver for goals with constraints in theories defined by unconstrained equalities and rewrite rules with constraints ex ..."
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Cited by 5 (4 self)
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Narrowing is a way to integrate function evaluation and equality definition into logic programming. Here we show how this can be combined with the constraint paradigm. We propose a solver for goals with constraints in theories defined by unconstrained equalities and rewrite rules with constraints expressed in an algebraic builtin structure. The narrowing method reduces the goal solving problem in the whole theory to rewriting and constraint solving in an adequate combined theory. The combined solver is obtained through the combination of a solver in the builtin structure and a solver for the unconstrained equalities. Sufficient syntactic conditions are proposed to get a process that enumerates a complete set of solutions. 1 Introduction Narrowing provides integration of function evaluation and equality definition into logic programming [6, 12, 8, 18, 10]. In this work, we show how this can be connected with the constraint paradigm to get a constraint solver on combined algebraic dom...
Sort Inheritance for OrderSorted Equational Presentations
 In Recent Trends in Data Types Specification
, 1995
"... In an algebraic framework, where equational, membership and existence formulas can be expressed, decorated terms and rewriting provide operational semantics and decision procedures for these formulas. We focus in this work on testing sort inheritance, an undecidable property of specifications, neede ..."
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Cited by 5 (4 self)
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In an algebraic framework, where equational, membership and existence formulas can be expressed, decorated terms and rewriting provide operational semantics and decision procedures for these formulas. We focus in this work on testing sort inheritance, an undecidable property of specifications, needed for unification in this context. A test and three specific processes, based on completion of a set of rewrite rules, are proposed to check sort inheritance. They depend on the kinds of membership formulas (t : A) allowed in the specifications: flat and linear, shallow and general terms t are studied.
OrderSorted Termination: the Unsorted Way
 In Proceedings from NIK'95: Norwegian Conference on Informatics, Gran (Hadeland
, 1996
"... We consider the problem of proving termination of ordersorted rewrite systems. The dominating method for proving termination of ordersorted systems has been to simply ignore sort information, and use the techniques developed for unsorted rewriting. The problem with this approach is that many order ..."
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Cited by 4 (0 self)
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We consider the problem of proving termination of ordersorted rewrite systems. The dominating method for proving termination of ordersorted systems has been to simply ignore sort information, and use the techniques developed for unsorted rewriting. The problem with this approach is that many ordersorted rewrite systems terminate because of the structure of the set of sorts. In these cases the corresponding unsorted system would not terminate. In this paper we approach the problem of ordersorted termination by mapping the ordersorted rewrite system into an unsorted one suchthat termination of the latter implies termination of the former. By encoding sort information into the unsorted mapping, we are able to use general purpose termination orderings to prove termination of ordersorted rewrite systems whose termination depend on the sort hierarchy. We present a sequence of gradually stronger methods, and show that a previously published method is contained in ours as a special case. 1
Algebraic System Specification and Development: Survey and Annotated Bibliography  Second Edition 
, 1997
"... Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.5.4 Special Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.6 Semantics of Programming Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.6.1 Semantics of Ada . . . ..."
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Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.5.4 Special Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.6 Semantics of Programming Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.6.1 Semantics of Ada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.6.2 Action Semantics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.7 Specification Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 4.7.1 Early Algebraic Specification Languages . . . . . . . . . . . . . . . . . . . . . . . . 53 4.7.2 Recent Algebraic Specification Languages . . . . . . . . . . . . . . . . . . . . . . . 55 4.7.3 The Common Framework Initiative. . . . . . . . . . . . . . . . . . . . . . . . . . . 56 5 Methodology 57 5.1 Development Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 5.1.1 Applica...
From Search to Computation: Redundancy Criteria and Simplification at Work
"... Abstract. The concept of redundancy and simplification has been an ongoing theme in Harald Ganzinger’s work from his first contributions to equational completion to the various variants of the superposition calculus. When executed by a theorem prover, the inference rules of these calculi usually gen ..."
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Abstract. The concept of redundancy and simplification has been an ongoing theme in Harald Ganzinger’s work from his first contributions to equational completion to the various variants of the superposition calculus. When executed by a theorem prover, the inference rules of these calculi usually generate a tremendously growing search space. The redundancy and simplification concept is indispensable for cutting down this search space to a manageable size. For a number of subclasses of firstorder logic appropriate redundancy and simplification concepts even turn the superposition calculus into a decision procedure. Hence, the key to successfully applying firstorder theorem proving to a problem domain is to find those simplifications and redundancy criteria that fit this domain and can be effectively implemented. We present Harald Ganzinger’s work in the light of the simplification and redundancy techniques that have been developed for concrete problem areas. This includes a variant of contextual rewriting to decide a subclass of Euclidean geometry, ordered chaining techniques for ChurchRosser and priority queue proofs, contextual rewriting and historydependent complexities for the completion of conditional rewrite systems, rewriting with equivalences for theorem proving in set theory, soft typing for the exploration of sort information in the context of equations, and constraint inheritance for automated complexity analysis. 1