YES(?,O(n^2)) Problem: a__f(f(X)) -> a__c(f(g(f(X)))) a__c(X) -> d(X) a__h(X) -> a__c(d(X)) mark(f(X)) -> a__f(mark(X)) mark(c(X)) -> a__c(X) mark(h(X)) -> a__h(mark(X)) mark(g(X)) -> g(X) mark(d(X)) -> d(X) a__f(X) -> f(X) a__c(X) -> c(X) a__h(X) -> h(X) Proof: Matrix Interpretation Processor: dimension: 2 interpretation: [8] [h](x0) = x0 + [2], [1 0] [0] [c](x0) = [0 0]x0 + [2], [1 1] [mark](x0) = [0 1]x0, [9] [a__h](x0) = x0 + [2], [1 0] [0] [d](x0) = [0 0]x0 + [2], [1 0] [1] [a__c](x0) = [0 0]x0 + [2], [1 0] [0] [g](x0) = [0 0]x0 + [5], [4] [a__f](x0) = x0 + [3], [2] [f](x0) = x0 + [3] orientation: [6] [1 0] [5] a__f(f(X)) = X + [6] >= [0 0]X + [2] = a__c(f(g(f(X)))) [1 0] [1] [1 0] [0] a__c(X) = [0 0]X + [2] >= [0 0]X + [2] = d(X) [9] [1 0] [1] a__h(X) = X + [2] >= [0 0]X + [2] = a__c(d(X)) [1 1] [5] [1 1] [4] mark(f(X)) = [0 1]X + [3] >= [0 1]X + [3] = a__f(mark(X)) [1 0] [2] [1 0] [1] mark(c(X)) = [0 0]X + [2] >= [0 0]X + [2] = a__c(X) [1 1] [10] [1 1] [9] mark(h(X)) = [0 1]X + [2 ] >= [0 1]X + [2] = a__h(mark(X)) [1 0] [5] [1 0] [0] mark(g(X)) = [0 0]X + [5] >= [0 0]X + [5] = g(X) [1 0] [2] [1 0] [0] mark(d(X)) = [0 0]X + [2] >= [0 0]X + [2] = d(X) [4] [2] a__f(X) = X + [3] >= X + [3] = f(X) [1 0] [1] [1 0] [0] a__c(X) = [0 0]X + [2] >= [0 0]X + [2] = c(X) [9] [8] a__h(X) = X + [2] >= X + [2] = h(X) problem: Qed