YES We show the termination of the relative TRS R/S: R: +(|0|(),y) -> y +(s(x),y) -> s(+(x,y)) sum1(nil()) -> |0|() sum1(cons(x,y)) -> +(x,sum1(y)) sum2(nil(),z) -> z sum2(cons(x,y),z) -> sum2(y,+(x,z)) tests(|0|()) -> true() tests(s(x)) -> and(test(rands(rand(|0|()),nil())),x) test(done(y)) -> eq(f(y),g(y)) eq(x,x) -> true() rands(|0|(),y) -> done(y) rands(s(x),y) -> rands(x,|::|(rand(|0|()),y)) S: rand(x) -> x rand(x) -> rand(s(x)) -- SCC decomposition. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: +#(s(x),y) -> +#(x,y) p2: sum1#(cons(x,y)) -> +#(x,sum1(y)) p3: sum1#(cons(x,y)) -> sum1#(y) p4: sum2#(cons(x,y),z) -> sum2#(y,+(x,z)) p5: sum2#(cons(x,y),z) -> +#(x,z) p6: tests#(s(x)) -> test#(rands(rand(|0|()),nil())) p7: tests#(s(x)) -> rands#(rand(|0|()),nil()) p8: test#(done(y)) -> eq#(f(y),g(y)) p9: rands#(s(x),y) -> rands#(x,|::|(rand(|0|()),y)) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),y) -> s(+(x,y)) r3: sum1(nil()) -> |0|() r4: sum1(cons(x,y)) -> +(x,sum1(y)) r5: sum2(nil(),z) -> z r6: sum2(cons(x,y),z) -> sum2(y,+(x,z)) r7: tests(|0|()) -> true() r8: tests(s(x)) -> and(test(rands(rand(|0|()),nil())),x) r9: test(done(y)) -> eq(f(y),g(y)) r10: eq(x,x) -> true() r11: rands(|0|(),y) -> done(y) r12: rands(s(x),y) -> rands(x,|::|(rand(|0|()),y)) r13: rand(x) -> x r14: rand(x) -> rand(s(x)) The estimated dependency graph contains the following SCCs: {p4} {p3} {p1} {p9} -- Reduction pair. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: sum2#(cons(x,y),z) -> sum2#(y,+(x,z)) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),y) -> s(+(x,y)) r3: sum1(nil()) -> |0|() r4: sum1(cons(x,y)) -> +(x,sum1(y)) r5: sum2(nil(),z) -> z r6: sum2(cons(x,y),z) -> sum2(y,+(x,z)) r7: tests(|0|()) -> true() r8: tests(s(x)) -> and(test(rands(rand(|0|()),nil())),x) r9: test(done(y)) -> eq(f(y),g(y)) r10: eq(x,x) -> true() r11: rands(|0|(),y) -> done(y) r12: rands(s(x),y) -> rands(x,|::|(rand(|0|()),y)) r13: rand(x) -> x r14: rand(x) -> rand(s(x)) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14 Take the reduction pair: lexicographic combination of reduction pairs: 1. lexicographic path order with precedence: precedence: test > eq > tests > true > sum2 > cons > sum1 > rands > |::| > done > g > + > s > f > rand > and > |0| > nil > sum2# argument filter: pi(sum2#) = [1, 2] pi(cons) = [1, 2] pi(+) = 2 pi(|0|) = [] pi(s) = 1 pi(sum1) = [1] pi(nil) = [] pi(sum2) = [1, 2] pi(tests) = [1] pi(true) = [] pi(and) = [] pi(test) = [1] pi(rands) = [] pi(rand) = [1] pi(done) = [] pi(eq) = [1] pi(f) = [] pi(g) = [] pi(|::|) = [] 2. matrix interpretations: carrier: N^2 order: lexicographic order interpretations: sum2#_A(x1,x2) = ((1,0),(1,1)) x1 + ((0,0),(1,0)) x2 cons_A(x1,x2) = ((1,0),(1,1)) x1 + ((0,0),(1,0)) x2 + (2,1) +_A(x1,x2) = ((1,0),(1,1)) x2 + (1,1) |0|_A() = (0,1) s_A(x1) = x1 sum1_A(x1) = (1,1) nil_A() = (1,0) sum2_A(x1,x2) = x1 + ((1,0),(1,1)) x2 + (0,1) tests_A(x1) = ((0,0),(1,0)) x1 true_A() = (0,0) and_A(x1,x2) = (1,1) test_A(x1) = (1,1) rands_A(x1,x2) = (1,1) rand_A(x1) = ((0,0),(1,0)) x1 + (1,1) done_A(x1) = (0,0) eq_A(x1,x2) = (0,0) f_A(x1) = (0,0) g_A(x1) = (0,0) |::|_A(x1,x2) = (1,0) The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: sum1#(cons(x,y)) -> sum1#(y) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),y) -> s(+(x,y)) r3: sum1(nil()) -> |0|() r4: sum1(cons(x,y)) -> +(x,sum1(y)) r5: sum2(nil(),z) -> z r6: sum2(cons(x,y),z) -> sum2(y,+(x,z)) r7: tests(|0|()) -> true() r8: tests(s(x)) -> and(test(rands(rand(|0|()),nil())),x) r9: test(done(y)) -> eq(f(y),g(y)) r10: eq(x,x) -> true() r11: rands(|0|(),y) -> done(y) r12: rands(s(x),y) -> rands(x,|::|(rand(|0|()),y)) r13: rand(x) -> x r14: rand(x) -> rand(s(x)) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14 Take the reduction pair: lexicographic combination of reduction pairs: 1. lexicographic path order with precedence: precedence: |::| > g > f > test > eq > done > rand > rands > tests > and > true > nil > sum1# > sum2 > sum1 > s > cons > |0| > + argument filter: pi(sum1#) = 1 pi(cons) = [1, 2] pi(+) = [1, 2] pi(|0|) = [] pi(s) = 1 pi(sum1) = 1 pi(nil) = [] pi(sum2) = [1, 2] pi(tests) = [1] pi(true) = [] pi(and) = [] pi(test) = [1] pi(rands) = 2 pi(rand) = [1] pi(done) = 1 pi(eq) = [2] pi(f) = [1] pi(g) = 1 pi(|::|) = 2 2. matrix interpretations: carrier: N^2 order: lexicographic order interpretations: sum1#_A(x1) = ((1,0),(1,1)) x1 cons_A(x1,x2) = ((0,0),(1,0)) x1 + ((1,0),(1,0)) x2 + (3,1) +_A(x1,x2) = ((1,0),(1,1)) x1 + ((1,0),(1,1)) x2 + (4,1) |0|_A() = (0,1) s_A(x1) = x1 sum1_A(x1) = ((0,0),(1,0)) x1 + (1,1) nil_A() = (1,0) sum2_A(x1,x2) = ((1,0),(1,1)) x1 + ((1,0),(1,1)) x2 tests_A(x1) = ((1,0),(1,1)) x1 true_A() = (0,0) and_A(x1,x2) = (1,1) test_A(x1) = (1,1) rands_A(x1,x2) = x2 + (1,1) rand_A(x1) = ((1,0),(1,1)) x1 + (1,1) done_A(x1) = (0,0) eq_A(x1,x2) = (0,0) f_A(x1) = (0,0) g_A(x1) = (0,0) |::|_A(x1,x2) = ((1,0),(1,1)) x2 + (0,1) The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: +#(s(x),y) -> +#(x,y) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),y) -> s(+(x,y)) r3: sum1(nil()) -> |0|() r4: sum1(cons(x,y)) -> +(x,sum1(y)) r5: sum2(nil(),z) -> z r6: sum2(cons(x,y),z) -> sum2(y,+(x,z)) r7: tests(|0|()) -> true() r8: tests(s(x)) -> and(test(rands(rand(|0|()),nil())),x) r9: test(done(y)) -> eq(f(y),g(y)) r10: eq(x,x) -> true() r11: rands(|0|(),y) -> done(y) r12: rands(s(x),y) -> rands(x,|::|(rand(|0|()),y)) r13: rand(x) -> x r14: rand(x) -> rand(s(x)) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14 Take the reduction pair: lexicographic combination of reduction pairs: 1. lexicographic path order with precedence: precedence: |::| > g > rand > rands > tests > test > sum2 > nil > sum1 > |0| > +# > f > done > eq > and > true > cons > + > s argument filter: pi(+#) = [1] pi(s) = 1 pi(+) = [1, 2] pi(|0|) = [] pi(sum1) = 1 pi(nil) = [] pi(cons) = [1, 2] pi(sum2) = [1, 2] pi(tests) = [1] pi(true) = [] pi(and) = 2 pi(test) = [1] pi(rands) = [2] pi(rand) = [1] pi(done) = [] pi(eq) = [] pi(f) = 1 pi(g) = 1 pi(|::|) = 2 2. matrix interpretations: carrier: N^2 order: lexicographic order interpretations: +#_A(x1,x2) = x1 s_A(x1) = x1 + (0,1) +_A(x1,x2) = x1 + ((1,0),(1,1)) x2 + (2,1) |0|_A() = (1,1) sum1_A(x1) = x1 + (1,1) nil_A() = (1,1) cons_A(x1,x2) = ((0,0),(1,0)) x2 + (1,1) sum2_A(x1,x2) = x1 tests_A(x1) = (0,0) true_A() = (0,0) and_A(x1,x2) = (1,1) test_A(x1) = (1,1) rands_A(x1,x2) = ((1,0),(1,1)) x2 + (0,1) rand_A(x1) = x1 + (0,1) done_A(x1) = (1,0) eq_A(x1,x2) = (0,0) f_A(x1) = (0,0) g_A(x1) = (0,0) |::|_A(x1,x2) = x2 The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the non-minimal dependency pair problem (P, R), where P consists of p1: rands#(s(x),y) -> rands#(x,|::|(rand(|0|()),y)) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),y) -> s(+(x,y)) r3: sum1(nil()) -> |0|() r4: sum1(cons(x,y)) -> +(x,sum1(y)) r5: sum2(nil(),z) -> z r6: sum2(cons(x,y),z) -> sum2(y,+(x,z)) r7: tests(|0|()) -> true() r8: tests(s(x)) -> and(test(rands(rand(|0|()),nil())),x) r9: test(done(y)) -> eq(f(y),g(y)) r10: eq(x,x) -> true() r11: rands(|0|(),y) -> done(y) r12: rands(s(x),y) -> rands(x,|::|(rand(|0|()),y)) r13: rand(x) -> x r14: rand(x) -> rand(s(x)) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11, r12, r13, r14 Take the reduction pair: lexicographic combination of reduction pairs: 1. lexicographic path order with precedence: precedence: rands > done > cons > nil > rands# > test > f > sum2 > g > + > sum1 > rand > s > eq > and > tests > |0| > true > |::| argument filter: pi(rands#) = [1, 2] pi(s) = 1 pi(|::|) = 2 pi(rand) = 1 pi(|0|) = [] pi(+) = [1, 2] pi(sum1) = 1 pi(nil) = [] pi(cons) = [1, 2] pi(sum2) = [1, 2] pi(tests) = [1] pi(true) = [] pi(and) = 2 pi(test) = [1] pi(rands) = [1, 2] pi(done) = [1] pi(eq) = [1] pi(f) = [] pi(g) = [] 2. matrix interpretations: carrier: N^2 order: lexicographic order interpretations: rands#_A(x1,x2) = x1 s_A(x1) = x1 + (0,1) |::|_A(x1,x2) = ((0,0),(1,0)) x2 + (0,1) rand_A(x1) = ((1,0),(1,0)) x1 + (1,1) |0|_A() = (1,1) +_A(x1,x2) = x1 + ((1,0),(1,0)) x2 + (1,1) sum1_A(x1) = ((0,0),(1,0)) x1 + (0,1) nil_A() = (1,0) cons_A(x1,x2) = x2 + (2,1) sum2_A(x1,x2) = ((1,0),(1,0)) x1 + x2 tests_A(x1) = ((0,0),(1,0)) x1 true_A() = (0,0) and_A(x1,x2) = (1,1) test_A(x1) = (1,1) rands_A(x1,x2) = ((1,0),(1,0)) x1 + ((1,0),(1,0)) x2 done_A(x1) = (0,2) eq_A(x1,x2) = (0,0) f_A(x1) = (0,0) g_A(x1) = (0,0) The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.