YES Problem: c(c(x1)) -> a(a(a(b(b(b(x1)))))) b(b(b(a(x1)))) -> b(b(b(b(b(b(b(b(x1)))))))) b(b(c(c(x1)))) -> c(c(c(a(a(a(a(x1))))))) Proof: Arctic Interpretation Processor: dimension: 2 interpretation: [0 0 ] [a](x0) = [-& -&]x0, [0 0] [b](x0) = [0 0]x0, [0 1] [c](x0) = [0 0]x0 orientation: [1 1] [0 0 ] c(c(x1)) = [0 1]x1 >= [-& -&]x1 = a(a(a(b(b(b(x1)))))) [0 0] [0 0] b(b(b(a(x1)))) = [0 0]x1 >= [0 0]x1 = b(b(b(b(b(b(b(b(x1)))))))) [1 1] [1 1] b(b(c(c(x1)))) = [1 1]x1 >= [1 1]x1 = c(c(c(a(a(a(a(x1))))))) problem: b(b(b(a(x1)))) -> b(b(b(b(b(b(b(b(x1)))))))) b(b(c(c(x1)))) -> c(c(c(a(a(a(a(x1))))))) String Reversal Processor: a(b(b(b(x1)))) -> b(b(b(b(b(b(b(b(x1)))))))) c(c(b(b(x1)))) -> a(a(a(a(c(c(c(x1))))))) Bounds Processor: bound: 0 enrichment: match automaton: final states: {10,1} transitions: f30() -> 2* b0(5) -> 6* b0(7) -> 8* b0(2) -> 3* b0(9) -> 1* b0(4) -> 5* b0(6) -> 7* b0(8) -> 9* b0(3) -> 4* a0(15) -> 16* a0(14) -> 15* a0(16) -> 10* a0(13) -> 14* c0(12) -> 13* c0(2) -> 11* c0(11) -> 12* 10 -> 11,12 problem: Qed