YES We show the termination of the TRS R: b(x,y) -> c(a(c(y),a(|0|(),x))) a(y,x) -> y a(y,c(b(a(|0|(),x),|0|()))) -> b(a(c(b(|0|(),y)),x),|0|()) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: b#(x,y) -> a#(c(y),a(|0|(),x)) p2: b#(x,y) -> a#(|0|(),x) p3: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(a(c(b(|0|(),y)),x),|0|()) p4: a#(y,c(b(a(|0|(),x),|0|()))) -> a#(c(b(|0|(),y)),x) p5: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(|0|(),y) and R consists of: r1: b(x,y) -> c(a(c(y),a(|0|(),x))) r2: a(y,x) -> y r3: a(y,c(b(a(|0|(),x),|0|()))) -> b(a(c(b(|0|(),y)),x),|0|()) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4, p5} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: b#(x,y) -> a#(c(y),a(|0|(),x)) p2: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(|0|(),y) p3: b#(x,y) -> a#(|0|(),x) p4: a#(y,c(b(a(|0|(),x),|0|()))) -> a#(c(b(|0|(),y)),x) p5: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(a(c(b(|0|(),y)),x),|0|()) and R consists of: r1: b(x,y) -> c(a(c(y),a(|0|(),x))) r2: a(y,x) -> y r3: a(y,c(b(a(|0|(),x),|0|()))) -> b(a(c(b(|0|(),y)),x),|0|()) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = ((1,0),(0,0)) x1 + ((0,1),(0,0)) x2 + (77,0) a#_A(x1,x2) = ((1,1),(0,0)) x1 + ((1,0),(0,0)) x2 + (9,0) c_A(x1) = ((0,1),(0,0)) x1 + (1,10) a_A(x1,x2) = ((1,0),(1,1)) x1 + ((1,0),(1,0)) x2 + (14,0) |0|_A() = (42,1) b_A(x1,x2) = x1 + ((0,1),(1,0)) x2 + (70,32) precedence: a# = a = |0| > b# = c = b partial status: pi(b#) = [] pi(a#) = [] pi(c) = [] pi(a) = [1] pi(|0|) = [] pi(b) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = (0,0) a#_A(x1,x2) = (0,0) c_A(x1) = (2,2) a_A(x1,x2) = x1 + (1,1) |0|_A() = (2,2) b_A(x1,x2) = (3,2) precedence: |0| > a > b > b# = a# = c partial status: pi(b#) = [] pi(a#) = [] pi(c) = [] pi(a) = [1] pi(|0|) = [] pi(b) = [] The next rules are strictly ordered: p3 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: b#(x,y) -> a#(c(y),a(|0|(),x)) p2: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(|0|(),y) p3: a#(y,c(b(a(|0|(),x),|0|()))) -> a#(c(b(|0|(),y)),x) p4: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(a(c(b(|0|(),y)),x),|0|()) and R consists of: r1: b(x,y) -> c(a(c(y),a(|0|(),x))) r2: a(y,x) -> y r3: a(y,c(b(a(|0|(),x),|0|()))) -> b(a(c(b(|0|(),y)),x),|0|()) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: b#(x,y) -> a#(c(y),a(|0|(),x)) p2: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(a(c(b(|0|(),y)),x),|0|()) p3: a#(y,c(b(a(|0|(),x),|0|()))) -> a#(c(b(|0|(),y)),x) p4: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(|0|(),y) and R consists of: r1: b(x,y) -> c(a(c(y),a(|0|(),x))) r2: a(y,x) -> y r3: a(y,c(b(a(|0|(),x),|0|()))) -> b(a(c(b(|0|(),y)),x),|0|()) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = ((0,1),(0,0)) x1 + ((0,1),(0,0)) x2 + (6,0) a#_A(x1,x2) = ((0,1),(0,0)) x1 + ((1,0),(0,0)) x2 + (5,0) c_A(x1) = ((0,1),(0,0)) x1 a_A(x1,x2) = x1 + ((0,0),(1,0)) x2 |0|_A() = (0,2) b_A(x1,x2) = ((0,0),(0,1)) x1 + ((0,0),(0,1)) x2 + (0,1) precedence: b# = a = b > c > |0| > a# partial status: pi(b#) = [] pi(a#) = [] pi(c) = [] pi(a) = [1] pi(|0|) = [] pi(b) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: b#_A(x1,x2) = (0,0) a#_A(x1,x2) = (1,0) c_A(x1) = (2,2) a_A(x1,x2) = ((1,0),(1,0)) x1 + (4,4) |0|_A() = (0,1) b_A(x1,x2) = (3,3) precedence: c = b > a# = a > |0| > b# partial status: pi(b#) = [] pi(a#) = [] pi(c) = [] pi(a) = [] pi(|0|) = [] pi(b) = [] The next rules are strictly ordered: p1, p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: a#(y,c(b(a(|0|(),x),|0|()))) -> a#(c(b(|0|(),y)),x) p2: a#(y,c(b(a(|0|(),x),|0|()))) -> b#(|0|(),y) and R consists of: r1: b(x,y) -> c(a(c(y),a(|0|(),x))) r2: a(y,x) -> y r3: a(y,c(b(a(|0|(),x),|0|()))) -> b(a(c(b(|0|(),y)),x),|0|()) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: a#(y,c(b(a(|0|(),x),|0|()))) -> a#(c(b(|0|(),y)),x) and R consists of: r1: b(x,y) -> c(a(c(y),a(|0|(),x))) r2: a(y,x) -> y r3: a(y,c(b(a(|0|(),x),|0|()))) -> b(a(c(b(|0|(),y)),x),|0|()) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: a#_A(x1,x2) = ((0,1),(0,1)) x2 + (7,13) c_A(x1) = ((0,0),(1,0)) x1 + (0,1) b_A(x1,x2) = x1 + ((0,1),(1,0)) x2 + (0,11) a_A(x1,x2) = ((1,1),(1,1)) x1 + ((0,1),(0,1)) x2 + (1,3) |0|_A() = (0,5) precedence: a = |0| > a# = c = b partial status: pi(a#) = [] pi(c) = [] pi(b) = [] pi(a) = [] pi(|0|) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: a#_A(x1,x2) = (0,0) c_A(x1) = (2,0) b_A(x1,x2) = (3,0) a_A(x1,x2) = (4,1) |0|_A() = (1,0) precedence: b > a# = c > a = |0| partial status: pi(a#) = [] pi(c) = [] pi(b) = [] pi(a) = [] pi(|0|) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.