YES(?,O(n^1)) Problem: s(a()) -> a() s(s(x)) -> x s(f(x,y)) -> f(s(y),s(x)) s(g(x,y)) -> g(s(x),s(y)) f(x,a()) -> x f(a(),y) -> y f(g(x,y),g(u,v)) -> g(f(x,u),f(y,v)) g(a(),a()) -> a() Proof: Bounds Processor: bound: 1 enrichment: match automaton: final states: {4,3,2} transitions: a1() -> 4,2 s0(1) -> 2* a0() -> 1* f0(1,1) -> 3* g0(1,1) -> 4* 1 -> 3* problem: Qed