ceta_eq: termination proof not accepted 1: error below switch to dependency pairs 1.1: error below the dependency graph processor 1.1.1: error when applying the reduction pair processor with usable rules to remove from the DP problem pairs: top#(mark(X)) -> top#(proper(X)) top#(ok(X)) -> top#(active(X)) rules: active(and(tt, X)) -> mark(X) active(plus(N, 0)) -> mark(N) active(plus(N, s(M))) -> mark(s(plus(N, M))) active(x(N, 0)) -> mark(0) active(x(N, s(M))) -> mark(plus(x(N, M), N)) active(and(X1, X2)) -> and(active(X1), X2) active(plus(X1, X2)) -> plus(active(X1), X2) active(plus(X1, X2)) -> plus(X1, active(X2)) active(s(X)) -> s(active(X)) active(x(X1, X2)) -> x(active(X1), X2) active(x(X1, X2)) -> x(X1, active(X2)) and(mark(X1), X2) -> mark(and(X1, X2)) and(ok(X1), ok(X2)) -> ok(and(X1, X2)) plus(mark(X1), X2) -> mark(plus(X1, X2)) plus(X1, mark(X2)) -> mark(plus(X1, X2)) plus(ok(X1), ok(X2)) -> ok(plus(X1, X2)) proper(and(X1, X2)) -> and(proper(X1), proper(X2)) proper(tt) -> ok(tt) proper(plus(X1, X2)) -> plus(proper(X1), proper(X2)) proper(0) -> ok(0) proper(s(X)) -> s(proper(X)) proper(x(X1, X2)) -> x(proper(X1), proper(X2)) s(mark(X)) -> mark(s(X)) s(ok(X)) -> ok(s(X)) top(mark(X)) -> top(proper(X)) top(ok(X)) -> top(active(X)) x(mark(X1), X2) -> mark(x(X1, X2)) x(X1, mark(X2)) -> mark(x(X1, X2)) x(ok(X1), ok(X2)) -> ok(x(X1, X2)) the pairs top#(mark(X)) -> top#(proper(X)) could not apply the generic reduction pair processor with the following Argument Filter: pi(top#/1) = [1] pi(ok/1) = 1 pi(active/1) = 1 pi(mark/1) = [1] pi(proper/1) = 1 pi(and/2) = [2,1] pi(tt/0) = [] pi(plus/2) = [2,1] pi(0/0) = [] pi(s/1) = [1] pi(x/2) = [1,2] RPO with the following precedence precedence(top#[1]) = 0 precedence(mark[1]) = 1 precedence(and[2]) = 2 precedence(tt[0]) = 3 precedence(plus[2]) = 4 precedence(0[0]) = 1 precedence(s[1]) = 1 precedence(x[2]) = 5 precedence(_) = 0 and the following status status(top#[1]) = mul status(mark[1]) = mul status(and[2]) = lex status(tt[0]) = mul status(plus[2]) = lex status(0[0]) = mul status(s[1]) = mul status(x[2]) = mul status(_) = lex problem when orienting (usable) rules could not orient s(mark(X)) >= mark(s(X)) pi( s(mark(X)) ) = s(mark(X)) pi( mark(s(X)) ) = mark(s(X)) could not orient s(mark(X)) >=RPO mark(s(X))