YES We show the termination of the TRS R: +(+(x,y),z) -> +(x,+(y,z)) +(f(x),f(y)) -> f(+(x,y)) +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: +#(+(x,y),z) -> +#(x,+(y,z)) p2: +#(+(x,y),z) -> +#(y,z) p3: +#(f(x),f(y)) -> +#(x,y) p4: +#(f(x),+(f(y),z)) -> +#(f(+(x,y)),z) p5: +#(f(x),+(f(y),z)) -> +#(x,y) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) 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: +#(+(x,y),z) -> +#(x,+(y,z)) p2: +#(f(x),+(f(y),z)) -> +#(x,y) p3: +#(f(x),+(f(y),z)) -> +#(f(+(x,y)),z) p4: +#(f(x),f(y)) -> +#(x,y) p5: +#(+(x,y),z) -> +#(y,z) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) 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: max/plus interpretations on natural numbers: +#_A(x1,x2) = max{x1 + 4, x2 + 4} +_A(x1,x2) = max{1, x1, x2} f_A(x1) = max{3, x1 + 2} precedence: +# = + > f partial status: pi(+#) = [] pi(+) = [] pi(f) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: +#_A(x1,x2) = 0 +_A(x1,x2) = 11 f_A(x1) = max{15, x1 + 11} precedence: f > + > +# partial status: pi(+#) = [] pi(+) = [] pi(f) = [] 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: +#(+(x,y),z) -> +#(x,+(y,z)) p2: +#(f(x),+(f(y),z)) -> +#(f(+(x,y)),z) p3: +#(f(x),f(y)) -> +#(x,y) p4: +#(+(x,y),z) -> +#(y,z) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) 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: +#(+(x,y),z) -> +#(x,+(y,z)) p2: +#(+(x,y),z) -> +#(y,z) p3: +#(f(x),f(y)) -> +#(x,y) p4: +#(f(x),+(f(y),z)) -> +#(f(+(x,y)),z) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) 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: max/plus interpretations on natural numbers: +#_A(x1,x2) = x2 + 2 +_A(x1,x2) = x2 f_A(x1) = max{4, x1 + 3} precedence: +# = + > f partial status: pi(+#) = [] pi(+) = [] pi(f) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: +#_A(x1,x2) = 0 +_A(x1,x2) = 6 f_A(x1) = x1 + 8 precedence: f > + > +# partial status: pi(+#) = [] pi(+) = [] pi(f) = [1] 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: +#(+(x,y),z) -> +#(x,+(y,z)) p2: +#(+(x,y),z) -> +#(y,z) p3: +#(f(x),+(f(y),z)) -> +#(f(+(x,y)),z) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) 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: +#(+(x,y),z) -> +#(x,+(y,z)) p2: +#(+(x,y),z) -> +#(y,z) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) 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: max/plus interpretations on natural numbers: +#_A(x1,x2) = x1 + 6 +_A(x1,x2) = max{3, x1 + 2, x2} f_A(x1) = 0 precedence: +# > + = f partial status: pi(+#) = [] pi(+) = [] pi(f) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: +#_A(x1,x2) = 2 +_A(x1,x2) = 12 f_A(x1) = 6 precedence: + > +# = f partial status: pi(+#) = [] pi(+) = [] pi(f) = [] 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: +#(+(x,y),z) -> +#(y,z) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: +#(+(x,y),z) -> +#(y,z) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: +#_A(x1,x2) = max{x1 + 1, x2} +_A(x1,x2) = max{x1 - 1, x2} precedence: +# = + partial status: pi(+#) = [1, 2] pi(+) = [2] 2. weighted path order base order: max/plus interpretations on natural numbers: +#_A(x1,x2) = max{x1 - 1, x2 + 1} +_A(x1,x2) = x2 precedence: +# = + partial status: pi(+#) = [] pi(+) = [2] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: +#(f(x),+(f(y),z)) -> +#(f(+(x,y)),z) and R consists of: r1: +(+(x,y),z) -> +(x,+(y,z)) r2: +(f(x),f(y)) -> f(+(x,y)) r3: +(f(x),+(f(y),z)) -> +(f(+(x,y)),z) 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(x1,x2) = x2 + (4,2) f_A(x1) = (3,1) +_A(x1,x2) = x1 + x2 + (2,2) precedence: +# = f = + partial status: pi(+#) = [] pi(f) = [] pi(+) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: +#_A(x1,x2) = ((1,0),(0,0)) x2 + (1,2) f_A(x1) = (2,1) +_A(x1,x2) = x1 + x2 + (0,3) precedence: +# = f = + partial status: pi(+#) = [] pi(f) = [] pi(+) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.