YES Problem: a(a(x1)) -> b(b(x1)) c(c(b(x1))) -> d(c(a(x1))) a(x1) -> d(c(c(x1))) c(d(x1)) -> b(c(x1)) Proof: Matrix Interpretation Processor: dim=3 interpretation: [1 0 1] [0] [b](x0) = [0 0 0]x0 + [1] [0 0 0] [0], [1 0 0] [d](x0) = [0 0 0]x0 [0 0 0] , [1 0 1] [0] [a](x0) = [1 0 1]x0 + [0] [1 0 0] [1], [1 0 0] [0] [c](x0) = [0 1 0]x0 + [1] [0 0 0] [0] orientation: [2 0 1] [1] [1 0 1] [0] a(a(x1)) = [2 0 1]x1 + [1] >= [0 0 0]x1 + [1] = b(b(x1)) [1 0 1] [1] [0 0 0] [0] [1 0 1] [0] [1 0 1] c(c(b(x1))) = [0 0 0]x1 + [3] >= [0 0 0]x1 = d(c(a(x1))) [0 0 0] [0] [0 0 0] [1 0 1] [0] [1 0 0] a(x1) = [1 0 1]x1 + [0] >= [0 0 0]x1 = d(c(c(x1))) [1 0 0] [1] [0 0 0] [1 0 0] [0] [1 0 0] [0] c(d(x1)) = [0 0 0]x1 + [1] >= [0 0 0]x1 + [1] = b(c(x1)) [0 0 0] [0] [0 0 0] [0] problem: c(c(b(x1))) -> d(c(a(x1))) a(x1) -> d(c(c(x1))) c(d(x1)) -> b(c(x1)) String Reversal Processor: b(c(c(x1))) -> a(c(d(x1))) a(x1) -> c(c(d(x1))) d(c(x1)) -> c(b(x1)) DP Processor: DPs: b#(c(c(x1))) -> d#(x1) b#(c(c(x1))) -> a#(c(d(x1))) a#(x1) -> d#(x1) d#(c(x1)) -> b#(x1) TRS: b(c(c(x1))) -> a(c(d(x1))) a(x1) -> c(c(d(x1))) d(c(x1)) -> c(b(x1)) TDG Processor: DPs: b#(c(c(x1))) -> d#(x1) b#(c(c(x1))) -> a#(c(d(x1))) a#(x1) -> d#(x1) d#(c(x1)) -> b#(x1) TRS: b(c(c(x1))) -> a(c(d(x1))) a(x1) -> c(c(d(x1))) d(c(x1)) -> c(b(x1)) graph: a#(x1) -> d#(x1) -> d#(c(x1)) -> b#(x1) d#(c(x1)) -> b#(x1) -> b#(c(c(x1))) -> a#(c(d(x1))) d#(c(x1)) -> b#(x1) -> b#(c(c(x1))) -> d#(x1) b#(c(c(x1))) -> a#(c(d(x1))) -> a#(x1) -> d#(x1) b#(c(c(x1))) -> d#(x1) -> d#(c(x1)) -> b#(x1) Matrix Interpretation Processor: dim=4 interpretation: [b#](x0) = [0 0 1 0]x0, [0 0 1 0] [0 0 1 0] [b](x0) = [0 0 1 0]x0 [0 0 1 0] , [0 1 0 0] [0] [0 1 0 0] [0] [d](x0) = [0 1 0 0]x0 + [0] [0 1 0 0] [1], [d#](x0) = [0 1 0 0]x0, [0 1 0 0] [0] [0 1 0 0] [1] [a](x0) = [0 1 0 0]x0 + [1] [0 1 0 0] [1], [a#](x0) = [0 1 0 0]x0, [1 0 0 0] [0] [0 0 1 0] [0] [c](x0) = [0 0 0 1]x0 + [0] [0 1 0 0] [1] orientation: b#(c(c(x1))) = [0 1 0 0]x1 + [1] >= [0 1 0 0]x1 = d#(x1) b#(c(c(x1))) = [0 1 0 0]x1 + [1] >= [0 1 0 0]x1 = a#(c(d(x1))) a#(x1) = [0 1 0 0]x1 >= [0 1 0 0]x1 = d#(x1) d#(c(x1)) = [0 0 1 0]x1 >= [0 0 1 0]x1 = b#(x1) [0 1 0 0] [1] [0 1 0 0] [0] [0 1 0 0] [1] [0 1 0 0] [1] b(c(c(x1))) = [0 1 0 0]x1 + [1] >= [0 1 0 0]x1 + [1] = a(c(d(x1))) [0 1 0 0] [1] [0 1 0 0] [1] [0 1 0 0] [0] [0 1 0 0] [0] [0 1 0 0] [1] [0 1 0 0] [1] a(x1) = [0 1 0 0]x1 + [1] >= [0 1 0 0]x1 + [1] = c(c(d(x1))) [0 1 0 0] [1] [0 1 0 0] [1] [0 0 1 0] [0] [0 0 1 0] [0] [0 0 1 0] [0] [0 0 1 0] [0] d(c(x1)) = [0 0 1 0]x1 + [0] >= [0 0 1 0]x1 + [0] = c(b(x1)) [0 0 1 0] [1] [0 0 1 0] [1] problem: DPs: a#(x1) -> d#(x1) d#(c(x1)) -> b#(x1) TRS: b(c(c(x1))) -> a(c(d(x1))) a(x1) -> c(c(d(x1))) d(c(x1)) -> c(b(x1)) Restore Modifier: DPs: a#(x1) -> d#(x1) d#(c(x1)) -> b#(x1) TRS: b(c(c(x1))) -> a(c(d(x1))) a(x1) -> c(c(d(x1))) d(c(x1)) -> c(b(x1)) EDG Processor: DPs: a#(x1) -> d#(x1) d#(c(x1)) -> b#(x1) TRS: b(c(c(x1))) -> a(c(d(x1))) a(x1) -> c(c(d(x1))) d(c(x1)) -> c(b(x1)) graph: a#(x1) -> d#(x1) -> d#(c(x1)) -> b#(x1) SCC Processor: #sccs: 0 #rules: 0 #arcs: 1/4