YES We show the termination of the TRS R: f(X) -> if(X,c(),n__f(true())) if(true(),X,Y) -> X if(false(),X,Y) -> activate(Y) f(X) -> n__f(X) activate(n__f(X)) -> f(X) activate(X) -> X -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(X) -> if#(X,c(),n__f(true())) p2: if#(false(),X,Y) -> activate#(Y) p3: activate#(n__f(X)) -> f#(X) and R consists of: r1: f(X) -> if(X,c(),n__f(true())) r2: if(true(),X,Y) -> X r3: if(false(),X,Y) -> activate(Y) r4: f(X) -> n__f(X) r5: activate(n__f(X)) -> f(X) r6: activate(X) -> X The estimated dependency graph contains the following SCCs: {p1, p2, p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(X) -> if#(X,c(),n__f(true())) p2: if#(false(),X,Y) -> activate#(Y) p3: activate#(n__f(X)) -> f#(X) and R consists of: r1: f(X) -> if(X,c(),n__f(true())) r2: if(true(),X,Y) -> X r3: if(false(),X,Y) -> activate(Y) r4: f(X) -> n__f(X) r5: activate(n__f(X)) -> f(X) r6: activate(X) -> X The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1) = ((1,0),(1,0)) x1 + (2,3) if#_A(x1,x2,x3) = ((1,0),(1,0)) x1 + ((1,0),(1,1)) x3 c_A() = (1,0) n__f_A(x1) = ((1,0),(0,0)) x1 + (1,1) true_A() = (0,1) false_A() = (4,4) activate#_A(x1) = ((1,0),(1,0)) x1 + (2,3) precedence: f# = c = n__f = true > if# = false = activate# partial status: pi(f#) = [] pi(if#) = [3] pi(c) = [] pi(n__f) = [] pi(true) = [] pi(false) = [] pi(activate#) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1) = (2,2) if#_A(x1,x2,x3) = (1,1) c_A() = (0,0) n__f_A(x1) = (3,3) true_A() = (1,1) false_A() = (4,4) activate#_A(x1) = (3,3) precedence: true > n__f > false > activate# > f# = c > if# partial status: pi(f#) = [] pi(if#) = [] pi(c) = [] pi(n__f) = [] pi(true) = [] pi(false) = [] pi(activate#) = [] The next rules are strictly ordered: p2, p3 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(X) -> if#(X,c(),n__f(true())) and R consists of: r1: f(X) -> if(X,c(),n__f(true())) r2: if(true(),X,Y) -> X r3: if(false(),X,Y) -> activate(Y) r4: f(X) -> n__f(X) r5: activate(n__f(X)) -> f(X) r6: activate(X) -> X The estimated dependency graph contains the following SCCs: (no SCCs)