YES Problem: a(b(a(a(x1)))) -> c(b(a(b(a(x1))))) a(c(b(x1))) -> a(a(b(c(b(a(x1)))))) Proof: String Reversal Processor: a(a(b(a(x1)))) -> a(b(a(b(c(x1))))) b(c(a(x1))) -> a(b(c(b(a(a(x1)))))) Bounds Processor: bound: 4 enrichment: match automaton: final states: {3,2,1} transitions: b3(107) -> 108* b3(109) -> 110* b3(121) -> 122* b3(123) -> 124* c3(108) -> 109* c3(120) -> 121* a4(131) -> 132* a4(135) -> 136* a4(130) -> 131* b4(132) -> 133* b4(134) -> 135* a0(2) -> 1* a0(1) -> 1* a0(3) -> 1* c4(133) -> 134* b0(2) -> 2* b0(1) -> 2* b0(3) -> 2* c0(2) -> 3* c0(1) -> 3* c0(3) -> 3* a1(42) -> 43* a1(32) -> 33* a1(7) -> 8* a1(9) -> 10* a1(36) -> 37* a1(31) -> 32* a1(38) -> 39* b1(35) -> 36* b1(6) -> 7* b1(73) -> 74* b1(33) -> 34* b1(8) -> 9* c1(50) -> 51* c1(5) -> 6* c1(52) -> 53* c1(22) -> 23* c1(34) -> 35* c1(24) -> 25* c1(90) -> 91* a2(75) -> 76* a2(96) -> 97* a2(86) -> 87* a2(76) -> 77* a2(46) -> 47* a2(48) -> 49* a2(80) -> 81* b2(45) -> 46* b2(77) -> 78* b2(47) -> 48* b2(79) -> 80* c2(44) -> 45* c2(88) -> 89* c2(78) -> 79* a3(122) -> 123* a3(124) -> 125* a3(106) -> 107* a3(128) -> 129* a3(110) -> 111* a3(105) -> 106* 1 -> 38,22 2 -> 31,5 3 -> 42,24 7 -> 44* 9 -> 86,52 10 -> 33,39,1 23 -> 6* 25 -> 6* 32 -> 73* 36 -> 75,50 37 -> 7,2 39 -> 32* 43 -> 32* 46 -> 120,88 48 -> 90* 49 -> 96,77,33,1,39 51 -> 45* 53 -> 45* 74 -> 34* 80 -> 105* 81 -> 46,7 87 -> 76* 89 -> 45* 91 -> 6* 97 -> 77* 110 -> 130* 111 -> 122,128,46 125 -> 97,77 129 -> 107* 136 -> 122* problem: Qed