YES We show the termination of the TRS R: minus(x,|0|()) -> x minus(s(x),s(y)) -> minus(x,y) double(|0|()) -> |0|() double(s(x)) -> s(s(double(x))) plus(|0|(),y) -> y plus(s(x),y) -> s(plus(x,y)) plus(s(x),y) -> plus(x,s(y)) plus(s(x),y) -> s(plus(minus(x,y),double(y))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: minus#(s(x),s(y)) -> minus#(x,y) p2: double#(s(x)) -> double#(x) p3: plus#(s(x),y) -> plus#(x,y) p4: plus#(s(x),y) -> plus#(x,s(y)) p5: plus#(s(x),y) -> plus#(minus(x,y),double(y)) p6: plus#(s(x),y) -> minus#(x,y) p7: plus#(s(x),y) -> double#(y) and R consists of: r1: minus(x,|0|()) -> x r2: minus(s(x),s(y)) -> minus(x,y) r3: double(|0|()) -> |0|() r4: double(s(x)) -> s(s(double(x))) r5: plus(|0|(),y) -> y r6: plus(s(x),y) -> s(plus(x,y)) r7: plus(s(x),y) -> plus(x,s(y)) r8: plus(s(x),y) -> s(plus(minus(x,y),double(y))) The estimated dependency graph contains the following SCCs: {p3, p4, p5} {p1} {p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: plus#(s(x),y) -> plus#(minus(x,y),double(y)) p2: plus#(s(x),y) -> plus#(x,s(y)) p3: plus#(s(x),y) -> plus#(x,y) and R consists of: r1: minus(x,|0|()) -> x r2: minus(s(x),s(y)) -> minus(x,y) r3: double(|0|()) -> |0|() r4: double(s(x)) -> s(s(double(x))) r5: plus(|0|(),y) -> y r6: plus(s(x),y) -> s(plus(x,y)) r7: plus(s(x),y) -> plus(x,s(y)) r8: plus(s(x),y) -> s(plus(minus(x,y),double(y))) The set of usable rules consists of r1, r2, r3, r4 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: plus#_A(x1,x2) = ((1,1),(1,1)) x1 + (2,1) s_A(x1) = x1 minus_A(x1,x2) = x1 double_A(x1) = x1 + (1,2) |0|_A() = (1,0) precedence: double > s > plus# > minus > |0| partial status: pi(plus#) = [1] pi(s) = [1] pi(minus) = [1] pi(double) = [1] pi(|0|) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: plus#_A(x1,x2) = ((1,0),(1,0)) x1 + (1,0) s_A(x1) = x1 + (3,7) minus_A(x1,x2) = (1,8) double_A(x1) = ((0,1),(0,1)) x1 + (5,8) |0|_A() = (1,1) precedence: plus# = minus > s = double = |0| partial status: pi(plus#) = [] pi(s) = [] pi(minus) = [] pi(double) = [] pi(|0|) = [] The next rules are strictly ordered: p1, p2, p3 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: minus#(s(x),s(y)) -> minus#(x,y) and R consists of: r1: minus(x,|0|()) -> x r2: minus(s(x),s(y)) -> minus(x,y) r3: double(|0|()) -> |0|() r4: double(s(x)) -> s(s(double(x))) r5: plus(|0|(),y) -> y r6: plus(s(x),y) -> s(plus(x,y)) r7: plus(s(x),y) -> plus(x,s(y)) r8: plus(s(x),y) -> s(plus(minus(x,y),double(y))) 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: minus#_A(x1,x2) = max{2, x1 - 1, x2 + 1} s_A(x1) = max{1, x1} precedence: minus# = s partial status: pi(minus#) = [2] pi(s) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: minus#_A(x1,x2) = 0 s_A(x1) = max{2, x1} precedence: minus# = s partial status: pi(minus#) = [] pi(s) = [1] 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: double#(s(x)) -> double#(x) and R consists of: r1: minus(x,|0|()) -> x r2: minus(s(x),s(y)) -> minus(x,y) r3: double(|0|()) -> |0|() r4: double(s(x)) -> s(s(double(x))) r5: plus(|0|(),y) -> y r6: plus(s(x),y) -> s(plus(x,y)) r7: plus(s(x),y) -> plus(x,s(y)) r8: plus(s(x),y) -> s(plus(minus(x,y),double(y))) 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: double#_A(x1) = max{4, x1 + 3} s_A(x1) = max{3, x1 + 2} precedence: double# = s partial status: pi(double#) = [1] pi(s) = [1] 2. weighted path order base order: max/plus interpretations on natural numbers: double#_A(x1) = max{1, x1 - 1} s_A(x1) = x1 precedence: double# = s partial status: pi(double#) = [] pi(s) = [1] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.