Grammar Adaptation

We employ transformations for the adaptation of grammars. Grammars need to be adapted in grammar development, grammar maintenance , grammar reengineering, and grammar recovery. Starting from a few fundamental transformation primitives and combinators, we derive an operator suite for grammar adaptation. Three groups of operators are identiied, namely operators for refactoring, construction and destruction. While refactoring is semantics-preserving in the narrow sense, transformations for construction and destruction require the consideration of relaxed notions of semantics preservation based on other grammar relations than equality of generated languages. The consideration of semantics and accompanying preservation properties is slightly complicated by the fact that we cannot insist on reduced grammars.