YES Problem: b(c(a(x1))) -> a(b(a(b(c(x1))))) b(x1) -> c(c(x1)) c(d(x1)) -> a(b(c(a(x1)))) a(a(x1)) -> a(c(b(a(x1)))) Proof: Arctic Interpretation Processor: dimension: 1 interpretation: [d](x0) = 7x0, [b](x0) = x0, [c](x0) = x0, [a](x0) = x0 orientation: b(c(a(x1))) = x1 >= x1 = a(b(a(b(c(x1))))) b(x1) = x1 >= x1 = c(c(x1)) c(d(x1)) = 7x1 >= x1 = a(b(c(a(x1)))) a(a(x1)) = x1 >= x1 = a(c(b(a(x1)))) problem: b(c(a(x1))) -> a(b(a(b(c(x1))))) b(x1) -> c(c(x1)) a(a(x1)) -> a(c(b(a(x1)))) String Reversal Processor: a(c(b(x1))) -> c(b(a(b(a(x1))))) b(x1) -> c(c(x1)) a(a(x1)) -> a(b(c(a(x1)))) Bounds Processor: bound: 1 enrichment: match automaton: final states: {9,7,1} transitions: a0(2) -> 3* a0(4) -> 5* a0(11) -> 9* c1(25) -> 26* c1(22) -> 23* c1(12) -> 13* c1(24) -> 25* c1(21) -> 22* c1(13) -> 14* f40() -> 2* c0(2) -> 8* c0(6) -> 1* c0(8) -> 7* c0(3) -> 10* b0(10) -> 11* b0(5) -> 6* b0(3) -> 4* 1 -> 3,21 3 -> 21* 5 -> 12* 9 -> 3,21 10 -> 24* 14 -> 6* 23 -> 4* 26 -> 11* problem: Qed