Term Rewriting Systems play an important role in various areas, such as abstract data type specifications, implementations of functional programming languages and automated deduction. In this chapter we introduce several of the basic comcepts and facts for TRS's. Specifically, we discuss Abstract Reduction Systems

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We present an approach for the generation of components for a software renovation factory. These components are generated from a context-free grammar definition that recognizes the code that has to be renovated. We generate analysis and transformation components that can be instantiated with a specific transformation or analysis task. We apply our approach to COBOL and we discuss the construction of realistic software renovation components using our approach.

In this paper we analyze completeness results for basic narrowing. We show that basic narrowing is not complete with respect to normalizable solutions for equational theories defined by confluent term rewriting systems, contrary to what has been conjectured. By imposing syntactic restrictions on the rewrite rules we recover completeness. We refute a result of Holldobler which states the completeness of basic conditional narrowing for complete (i.e. confluent and terminating) conditional term rewriting systems without extra variables in the conditions of the rewrite rules. In the last part of the paper we extend the completeness result of Giovannetti and Moiso for level-confluent and terminating conditional systems with extra variables in the conditions to systems that may also have extra variables in the right-hand sides of the rules. 1985 Mathematics Subject Classification: 68Q50 1987 CR Categories: F.4.1, F.4.2 Key Words and Phrases: narrowing, basic narrowing, conditional narrowin...

Functional and logic programming are the most important declarative programming paradigms, and interest in combining them has grown over the last decade. Early research concentrated on the definition and improvement of execution principles for such integrated languages, while more recently efficient implementations of these execution principles have been developed so that these languages became relevant for practical applications. In this paper we survey the development of the operational semantics as well as

We argue that maintenance and reengineering tools need to have a thorough knowledge of the language that the code is written in. More specifically, for the family of COBOL languages we present a general method to define COBOL dialects that are based on the actual code that has to be reengineered or maintained. Subsequently, we give some typical examples of maintenance and reengineering tools that have been specified on top of such a COBOL grammar in order to show that our approach is useful and leads to accurate and relatively simple maintenance and reengineering tools. Categories and Subject Description: D.2.6 [Software Engineering]: Programming Environments---Interactive; D.2.7 [Software Engineering]: Distribution and Maintenance ---Restructuring; D.2.m [Software Engineering]: Miscellaneous---Rapid prototyping Additional Key Words and Phrases: Reengineering, System renovation, COBOL 1 Introduction There is a constant need for updating and renovating business-critical software sys...

This paper is concerned with the impact of stepwise development methodologies on prototyping.

Conditional rewriting is universally recognized as being much more complicated than unconditional rewriting. In this paper we study how much of conditional rewriting can be automatically inferred from the simpler theory of unconditional rewriting. We introduce a new tool, called unraveling, to automatically translate a conditional term rewriting system (CTRS) into a term rewriting system (TRS). An unraveling enables to infer properties of a CTRS by studying the corresponding ultra-property on the corresponding TRS. We show how to rediscover properties like decreasingness, and to give easy proofs of some existing results on CTRSs. Moreover, we show how unravelings provide a valuable tool to study modularity of CTRSs, automatically giving a multitude of new results.

We generate a native pattern language from a context-free grammar. So if we have the underlying grammar of code that needs to be analyzed, or renovated the pattern language comes for free. We use native patterns for recognition and renovation of code. The pattern language is global in the sense that patterns can match entire programs. We illustrate native patterns by discussing a tool that remediates a notoriously difficult Year 2000 problem using native patterns. Categories and Subject Description: D.2.6 [Software Engineering ]: Programming Environments---Interactive; D.2.7 [Software Engineering]: Distribution and Maintenance--- Restructuring; D.3.4. [Processors]: Parsing. Additional Key Words and Phrases: Reengineering, System renovation, Patterns, Plans, Clich'es, Native pattern language, Year 2000 problem, Leap year problem. 1 Introduction One key task in reengineering software is the recognition of problematic code. For example, for Year 2000 related remediation, it is necessa...

Term rewriting has a large potential for industrial applications, but these applications are always larger than one could ever dream of: huge sets of rewrite rules and gigantic terms to rewrite pose interesting challenges for implementors and theoreticians alike. We give a brief overview of the generation of term-rewriting-based tools as done in the Asf+Sdf Meta-Environment and then we sketch two major applications of term rewriting: transformation of legacy COBOL systems and compilation of Asf+Sdf to C. Based on these experiences we suggest the study of topics that could further advance the use of term rewriting in industrial applications: persistent term databases, generalized LR parsing versus parallel term rewriting, and coordination languages versus strategy languages. It will turn out that we have an "alien" view on research in term rewriting: properties like confluence and termination are of very limited use when selling term rewriting to industry.