Problem: f(x,y) -> f(g(x),g(x)) f(g(x),x) -> f(x,g(x)) g(x) -> h(x) h(g(x)) -> g(g(x)) Proof: Church Rosser Transformation Processor: strict: weak: critical peaks: 4 f(g(g(x)),g(g(x))) <-0|[]- f(g(x),x) -1|[]-> f(x,g(x)) f(y,g(y)) <-1|[]- f(g(y),y) -0|[]-> f(g(g(y)),g(g(y))) f(h(x),x) <-2|0[]- f(g(x),x) -1|[]-> f(x,g(x)) h(h(x)) <-2|0[]- h(g(x)) -3|[]-> g(g(x)) Redundant Rules Transformation: f(x,y) -> f(g(x),g(x)) g(x) -> h(x) Church Rosser Transformation Processor (no redundant rules): strict: g(x) -> h(x) f(x,y) -> f(g(x),g(x)) weak: critical peaks: 0 Closedness Processor (*feeble*): Qed