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