Problem: f(x) -> g(a()) g(x) -> x h(x,x) -> 0() a() -> 1() Proof: sorted: (order) 0:f(x) -> g(a()) g(x) -> x a() -> 1() 1:h(x,x) -> 0() ----- sorts [0>1, 0>8, 1>5, 2>3, 2>4, 5>6, 6>7] sort attachment (non-strict) f : 8 -> 0 g : 5 -> 1 a : 6 h : 4 x 4 -> 2 0 : 3 1 : 7 ----- 0:f(x) -> g(a()) g(x) -> x a() -> 1() Church Rosser Transformation Processor (critical pair closing system, Thm 2.11): critical peaks: joinable Qed 1:h(x,x) -> 0() Qed (ToyamaOyamaguchi95Cor22)