YES We show the termination of the TRS R: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) f(a(x),a(y)) -> a(f(x,y)) f(b(x),b(y)) -> b(f(x,y)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: a#(a(f(x,y))) -> a#(b(a(b(a(x))))) p3: a#(a(f(x,y))) -> a#(b(a(x))) p4: a#(a(f(x,y))) -> a#(x) p5: a#(a(f(x,y))) -> a#(b(a(b(a(y))))) p6: a#(a(f(x,y))) -> a#(b(a(y))) p7: a#(a(f(x,y))) -> a#(y) p8: f#(a(x),a(y)) -> a#(f(x,y)) p9: f#(a(x),a(y)) -> f#(x,y) p10: f#(b(x),b(y)) -> f#(x,y) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) The estimated dependency graph contains the following SCCs: {p1, p4, p7, p8, p9, p10} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> f#(x,y) p3: f#(b(x),b(y)) -> f#(x,y) p4: f#(a(x),a(y)) -> a#(f(x,y)) p5: a#(a(f(x,y))) -> a#(y) p6: a#(a(f(x,y))) -> a#(x) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) 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: lexicographic order interpretations: a#_A(x1) = ((0,0),(1,0)) x1 + (4,4) a_A(x1) = ((1,0),(1,1)) x1 + (0,4) f_A(x1,x2) = x1 + x2 + (3,5) f#_A(x1,x2) = ((0,0),(1,0)) x1 + ((0,0),(1,0)) x2 + (4,7) b_A(x1) = ((1,0),(0,0)) x1 + (0,2) precedence: a# = a = f# > b > f partial status: pi(a#) = [] pi(a) = [] pi(f) = [2] pi(f#) = [] pi(b) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: a#_A(x1) = (3,2) a_A(x1) = (2,1) f_A(x1,x2) = (1,0) f#_A(x1,x2) = (3,2) b_A(x1) = (2,1) precedence: a > a# = f# > b > f partial status: pi(a#) = [] pi(a) = [] pi(f) = [] pi(f#) = [] pi(b) = [] The next rules are strictly ordered: p5 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> f#(x,y) p3: f#(b(x),b(y)) -> f#(x,y) p4: f#(a(x),a(y)) -> a#(f(x,y)) p5: a#(a(f(x,y))) -> a#(x) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) 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: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> a#(f(x,y)) p3: a#(a(f(x,y))) -> a#(x) p4: f#(a(x),a(y)) -> f#(x,y) p5: f#(b(x),b(y)) -> f#(x,y) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) 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: lexicographic order interpretations: a#_A(x1) = ((0,0),(1,0)) x1 + (1,1) a_A(x1) = ((1,0),(0,0)) x1 + (0,2) f_A(x1,x2) = ((1,0),(0,0)) x1 + (2,2) f#_A(x1,x2) = ((0,0),(1,0)) x1 + (1,3) b_A(x1) = ((1,0),(0,0)) x1 + (0,1) precedence: a# = a = f = f# > b partial status: pi(a#) = [] pi(a) = [] pi(f) = [] pi(f#) = [] pi(b) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: a#_A(x1) = (2,1) a_A(x1) = (3,2) f_A(x1,x2) = (3,2) f#_A(x1,x2) = (2,1) b_A(x1) = (1,3) precedence: a# = a = f = f# = b partial status: pi(a#) = [] pi(a) = [] pi(f) = [] pi(f#) = [] 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: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> a#(f(x,y)) p3: f#(a(x),a(y)) -> f#(x,y) p4: f#(b(x),b(y)) -> f#(x,y) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) 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: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> f#(x,y) p3: f#(b(x),b(y)) -> f#(x,y) p4: f#(a(x),a(y)) -> a#(f(x,y)) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) 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) = ((1,1),(1,1)) x1 + (1,1) a_A(x1) = ((0,0),(1,1)) x1 + (8,0) f_A(x1,x2) = x2 f#_A(x1,x2) = ((0,1),(0,1)) x2 + (1,2) b_A(x1) = ((0,0),(0,1)) x1 + (2,1) precedence: a# = a = f = f# > b partial status: pi(a#) = [] pi(a) = [] pi(f) = [] pi(f#) = [] pi(b) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: a#_A(x1) = (0,1) a_A(x1) = (0,1) f_A(x1,x2) = (0,1) f#_A(x1,x2) = (0,1) b_A(x1) = (0,1) precedence: a# = f# > a = f > b partial status: pi(a#) = [] pi(a) = [] pi(f) = [] pi(f#) = [] 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: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> f#(x,y) p3: f#(a(x),a(y)) -> a#(f(x,y)) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) 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: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> a#(f(x,y)) p3: f#(a(x),a(y)) -> f#(x,y) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) 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: lexicographic order interpretations: a#_A(x1) = ((1,0),(1,1)) x1 + (5,1) a_A(x1) = ((1,0),(1,1)) x1 + (4,0) f_A(x1,x2) = ((0,0),(1,0)) x1 + x2 + (3,3) f#_A(x1,x2) = x1 + ((1,0),(1,1)) x2 + (1,4) b_A(x1) = (1,1) precedence: a = f = b > a# = f# partial status: pi(a#) = [1] pi(a) = [1] pi(f) = [2] pi(f#) = [2] pi(b) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: a#_A(x1) = ((0,0),(1,0)) x1 + (0,1) a_A(x1) = (1,3) f_A(x1,x2) = (1,3) f#_A(x1,x2) = (0,2) b_A(x1) = (1,3) precedence: a = f = b > a# = f# partial status: pi(a#) = [] pi(a) = [] pi(f) = [] pi(f#) = [] 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: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> a#(f(x,y)) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: a#(a(f(x,y))) -> f#(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) p2: f#(a(x),a(y)) -> a#(f(x,y)) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) 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: lexicographic order interpretations: a#_A(x1) = ((0,0),(1,0)) x1 + (2,1) a_A(x1) = ((1,0),(0,0)) x1 + (4,9) f_A(x1,x2) = x2 + (3,5) f#_A(x1,x2) = ((0,0),(1,0)) x2 + (2,2) b_A(x1) = (1,10) precedence: f# > f = b > a# = a partial status: pi(a#) = [] pi(a) = [] pi(f) = [] pi(f#) = [] pi(b) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: a#_A(x1) = (2,2) a_A(x1) = (1,0) f_A(x1,x2) = (4,2) f#_A(x1,x2) = (3,1) b_A(x1) = (4,0) precedence: b > a# = a = f = f# partial status: pi(a#) = [] pi(a) = [] pi(f) = [] pi(f#) = [] pi(b) = [] The next rules are strictly ordered: p1 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(a(x),a(y)) -> a#(f(x,y)) and R consists of: r1: a(a(f(x,y))) -> f(a(b(a(b(a(x))))),a(b(a(b(a(y)))))) r2: f(a(x),a(y)) -> a(f(x,y)) r3: f(b(x),b(y)) -> b(f(x,y)) The estimated dependency graph contains the following SCCs: (no SCCs)