Programming Research Group  -  University of Amsterdam  -  TR P9802


	     Conservative Extension in Positive/Negative
	     Conditional Term Rewriting with Applications
		   to Software Renovation Factories


			     Wan Fokkink
			    Chris Verhoef


General theorems in structured operational semantics can be
transformed into related results in conditional term rewriting. We
apply this approach to give meaning to conditional term rewriting
systems with negative conditions, and to obtain a conservative
extension theorem for such systems. These results are useful for
development of software renovation factories, and for modular
specification of abstract data types.