YES Problem: a(c(b(x1))) -> b(a(b(a(x1)))) b(x1) -> c(a(c(x1))) a(a(x1)) -> a(b(c(a(x1)))) Proof: String Reversal Processor: b(c(a(x1))) -> a(b(a(b(x1)))) b(x1) -> c(a(c(x1))) a(a(x1)) -> a(c(b(a(x1)))) Bounds Processor: bound: 2 enrichment: match automaton: final states: {9,6,1} transitions: b0(4) -> 5* b0(2) -> 3* b0(10) -> 11* c1(13) -> 14* c1(31) -> 32* c1(39) -> 40* c1(27) -> 28* c1(15) -> 16* c1(29) -> 30* c1(25) -> 26* c0(2) -> 7* c0(8) -> 6* c0(11) -> 12* a2(48) -> 49* a0(3) -> 4* a0(12) -> 9* a0(2) -> 10* a0(7) -> 8* a0(5) -> 1* f30() -> 2* a1(40) -> 41* a1(37) -> 38* a1(30) -> 31* a1(14) -> 15* a1(26) -> 27* c2(49) -> 50* c2(47) -> 48* b1(38) -> 39* 16 -> 3* 28 -> 11* 4 -> 29* 2 -> 13* 38 -> 47* 1 -> 3* 5 -> 37* 9 -> 10,25 50 -> 39* 41 -> 4,29 10 -> 25* 32 -> 5* problem: Qed