YES O(n^5) TRS: { a__h(X) -> h(X), a__h(d()) -> a__g(c()), a__g(X) -> a__h(X), a__g(X) -> g(X), a__c() -> d(), a__c() -> c(), mark(d()) -> d(), mark(c()) -> a__c(), mark(g(X)) -> a__g(X), mark(h(X)) -> a__h(X) } DUP: We consider a non-duplicating system. Trs: { a__h(X) -> h(X), a__h(d()) -> a__g(c()), a__g(X) -> a__h(X), a__g(X) -> g(X), a__c() -> d(), a__c() -> c(), mark(d()) -> d(), mark(c()) -> a__c(), mark(g(X)) -> a__g(X), mark(h(X)) -> a__h(X) } Matrix Interpretation: Interpretation class: triangular [X4] [1 0 1 1 0][X4] [0] [X3] [0 0 3 3 0][X3] [0] [h]([X2]) = [0 0 0 0 0][X2] + [0] [X1] [0 0 0 0 1][X1] [0] [X0] [0 0 0 0 0][X0] [3] [X4] [1 0 0 2 0][X4] [0] [X3] [0 0 3 1 0][X3] [0] [g]([X2]) = [0 0 0 1 0][X2] + [0] [X1] [0 0 0 0 1][X1] [0] [X0] [0 0 0 0 0][X0] [3] [X4] [1 1 1 0 3][X4] [0] [X3] [0 1 2 3 0][X3] [0] [mark]([X2]) = [0 0 1 2 0][X2] + [2] [X1] [0 0 0 1 1][X1] [3] [X0] [0 0 0 0 0][X0] [3] [0] [2] [c] = [3] [1] [1] [3] [2] [a__c] = [3] [3] [2] [1] [0] [d] = [0] [3] [2] [X4] [1 0 1 2 0][X4] [3] [X3] [0 0 3 3 3][X3] [0] [a__g]([X2]) = [0 0 0 1 2][X2] + [1] [X1] [0 0 0 0 1][X1] [0] [X0] [0 0 0 0 0][X0] [3] [X4] [1 0 1 2 0][X4] [2] [X3] [0 0 3 3 3][X3] [0] [a__h]([X2]) = [0 0 0 0 2][X2] + [0] [X1] [0 0 0 0 1][X1] [0] [X0] [0 0 0 0 0][X0] [3] Qed