YES Problem: c(c(x)) -> x b(b(x)) -> B(x) B(B(x)) -> b(x) c(B(c(b(c(x))))) -> B(c(b(c(B(c(b(x))))))) b(B(x)) -> x B(b(x)) -> x Proof: AT confluence processor Complete TRS T' of input TRS: c(c(x)) -> x b(b(x)) -> B(x) B(B(x)) -> b(x) c(B(c(b(c(x))))) -> B(c(b(c(B(c(b(x))))))) b(B(x)) -> x B(b(x)) -> x T' = (P union S) with TRS P: TRS S:c(c(x)) -> x b(b(x)) -> B(x) B(B(x)) -> b(x) c(B(c(b(c(x))))) -> B(c(b(c(B(c(b(x))))))) b(B(x)) -> x B(b(x)) -> x S is left-linear and P is reversible. CP(S,S) = c(x193) = c(x193), c(B(c(b(x194)))) = B(c(b(c(B(c(b(c(x194)))))))), b(B(x195)) = B(b(x195)), B(B(x196)) = b(x196), B(b(x197)) = b(B(x197)), b(b(x198)) = B(x198), c(B(c(b(c(B(c(b(x199)))))))) = B(c(b(c(x199)))), c(B(c(b(B(c(b(c(B(c(b(x200))))))))))) = B(c(b(c(B(c(b(B(c(b(c(x200))))))))))), b(x201) = B(B(x201)), B(x202) = B(x202), B(x203) = b(b(x203)), b(x204) = b(x204) CP(S,P union P^-1) = PCP_in(P union P^-1,S) = We have to check termination of S: Matrix Interpretation Processor: dim=1 interpretation: [b](x0) = x0, [c](x0) = 2x0 + 1, [B](x0) = x0 orientation: c(c(x)) = 4x + 3 >= x = x b(b(x)) = x >= x = B(x) B(B(x)) = x >= x = b(x) c(B(c(b(c(x))))) = 8x + 7 >= 8x + 7 = B(c(b(c(B(c(b(x))))))) b(B(x)) = x >= x = x B(b(x)) = x >= x = x problem: b(b(x)) -> B(x) B(B(x)) -> b(x) c(B(c(b(c(x))))) -> B(c(b(c(B(c(b(x))))))) b(B(x)) -> x B(b(x)) -> x String Reversal Processor: b(b(x)) -> B(x) B(B(x)) -> b(x) c(b(c(B(c(x))))) -> b(c(B(c(b(c(B(x))))))) B(b(x)) -> x b(B(x)) -> x Bounds Processor: bound: 1 enrichment: match automaton: final states: {2,4,3,1} transitions: b0(9) -> 4* b0(2) -> 3* b0(5) -> 6* B1(10) -> 11* c0(6) -> 7* c0(1) -> 5* c0(8) -> 9* B0(2) -> 1* B0(7) -> 8* f30() -> 2* 4 -> 5,7 11 -> 6* 2 -> 1* 1 -> 3* 9 -> 10,8 3 -> 1* problem: Qed