YES We show the termination of the TRS R: if(true(),x,y) -> x if(false(),x,y) -> y if(x,y,y) -> y if(if(x,y,z),u(),v()) -> if(x,if(y,u(),v()),if(z,u(),v())) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: if#(if(x,y,z),u(),v()) -> if#(x,if(y,u(),v()),if(z,u(),v())) p2: if#(if(x,y,z),u(),v()) -> if#(y,u(),v()) p3: if#(if(x,y,z),u(),v()) -> if#(z,u(),v()) and R consists of: r1: if(true(),x,y) -> x r2: if(false(),x,y) -> y r3: if(x,y,y) -> y r4: if(if(x,y,z),u(),v()) -> if(x,if(y,u(),v()),if(z,u(),v())) 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: if#(if(x,y,z),u(),v()) -> if#(x,if(y,u(),v()),if(z,u(),v())) p2: if#(if(x,y,z),u(),v()) -> if#(z,u(),v()) p3: if#(if(x,y,z),u(),v()) -> if#(y,u(),v()) and R consists of: r1: if(true(),x,y) -> x r2: if(false(),x,y) -> y r3: if(x,y,y) -> y r4: if(if(x,y,z),u(),v()) -> if(x,if(y,u(),v()),if(z,u(),v())) The set of usable rules consists of r1, r2, r3, r4 Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: if#_A(x1,x2,x3) = ((1,1),(1,1)) x1 + ((0,0),(0,1)) x2 + ((0,0),(0,1)) x3 + (2,2) if_A(x1,x2,x3) = ((1,1),(1,1)) x1 + x2 + x3 + (1,1) u_A() = (0,0) v_A() = (0,0) true_A() = (1,0) false_A() = (1,0) precedence: if# = if = v = true > false > u partial status: pi(if#) = [] pi(if) = [] pi(u) = [] pi(v) = [] pi(true) = [] pi(false) = [] The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: if#(if(x,y,z),u(),v()) -> if#(x,if(y,u(),v()),if(z,u(),v())) p2: if#(if(x,y,z),u(),v()) -> if#(y,u(),v()) and R consists of: r1: if(true(),x,y) -> x r2: if(false(),x,y) -> y r3: if(x,y,y) -> y r4: if(if(x,y,z),u(),v()) -> if(x,if(y,u(),v()),if(z,u(),v())) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: if#(if(x,y,z),u(),v()) -> if#(x,if(y,u(),v()),if(z,u(),v())) p2: if#(if(x,y,z),u(),v()) -> if#(y,u(),v()) and R consists of: r1: if(true(),x,y) -> x r2: if(false(),x,y) -> y r3: if(x,y,y) -> y r4: if(if(x,y,z),u(),v()) -> if(x,if(y,u(),v()),if(z,u(),v())) The set of usable rules consists of r1, r2, r3, r4 Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: if#_A(x1,x2,x3) = ((1,1),(1,1)) x1 + ((0,1),(0,1)) x2 + ((0,1),(0,1)) x3 + (2,2) if_A(x1,x2,x3) = ((1,1),(1,1)) x1 + x2 + x3 + (1,1) u_A() = (0,0) v_A() = (0,0) true_A() = (1,1) false_A() = (1,1) precedence: if# = if > v = true = false > u partial status: pi(if#) = [] pi(if) = [] pi(u) = [] pi(v) = [] pi(true) = [] pi(false) = [] The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: if#(if(x,y,z),u(),v()) -> if#(x,if(y,u(),v()),if(z,u(),v())) and R consists of: r1: if(true(),x,y) -> x r2: if(false(),x,y) -> y r3: if(x,y,y) -> y r4: if(if(x,y,z),u(),v()) -> if(x,if(y,u(),v()),if(z,u(),v())) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: if#(if(x,y,z),u(),v()) -> if#(x,if(y,u(),v()),if(z,u(),v())) and R consists of: r1: if(true(),x,y) -> x r2: if(false(),x,y) -> y r3: if(x,y,y) -> y r4: if(if(x,y,z),u(),v()) -> if(x,if(y,u(),v()),if(z,u(),v())) The set of usable rules consists of r1, r2, r3, r4 Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: if#_A(x1,x2,x3) = ((1,0),(1,0)) x1 + (2,2) if_A(x1,x2,x3) = ((1,1),(1,1)) x1 + x2 + x3 + (1,1) u_A() = (0,0) v_A() = (0,0) true_A() = (1,0) false_A() = (1,0) precedence: if# = if > u = true = false > v partial status: pi(if#) = [] pi(if) = [] pi(u) = [] pi(v) = [] pi(true) = [] pi(false) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.