This volume contains the proceedings of the Fourth International Conference on Rewriting Techniques and Applications (RTA-91), held in Como, Italy, April 10-12, 1991. The volume includes 40 papers on a wide variety of topics including: term rewriting systems, equational unification, algebraic rewriting, termination proofs, generalization problems, undecidable properties, parametrized specifications, normalizing systems, program transformation, query optimization, tree languages, graph languages, theorem proving systems, completion, graph rewriting systems, and open problems.weiterlesen