YES (ignored inputs)COMMENT from the collection of \cite{AT2012} Rewrite Rules: [ +(0,?y) -> ?y, +(s(?x),?y) -> s(+(?x,?y)), inc(?x) -> s(?x), +(?x,?y) -> +(?y,?x), inc(+(?x,?y)) -> +(inc(?x),?y) ] Apply Direct Methods... Inner CPs: [ inc(?y) = +(inc(0),?y), inc(s(+(?x_1,?y_1))) = +(inc(s(?x_1)),?y_1), inc(+(?y_3,?x_3)) = +(inc(?x_3),?y_3) ] Outer CPs: [ ?y = +(?y,0), s(+(?x_1,?y_1)) = +(?y_1,s(?x_1)), s(+(?x_4,?y_4)) = +(inc(?x_4),?y_4) ] not Overlay, check Termination... unknown/not Terminating unknown Knuth & Bendix Linear unknown Development Closed unknown Strongly Closed unknown Weakly-Non-Overlapping & Non-Collapsing & Shallow unknown Upside-Parallel-Closed/Outside-Closed (inner) Parallel CPs: (not computed) unknown Toyama (Parallel CPs) Simultaneous CPs: [ +(?y,0) = ?y, +(inc(0),?y) = inc(?y), +(?y,s(?x)) = s(+(?x,?y)), +(inc(s(?x)),?y) = inc(s(+(?x,?y))), +(inc(?x_4),?y_4) = s(+(?x_4,?y_4)), ?y = +(?y,0), s(+(?x_2,?y)) = +(?y,s(?x_2)), +(inc(?x),?y) = inc(+(?y,?x)), s(?y) = +(inc(0),?y), s(s(+(?x_3,?y))) = +(inc(s(?x_3)),?y), s(+(?y,?x)) = +(inc(?x),?y), s(+(?x,?y)) = +(inc(?x),?y), inc(?y) = +(inc(0),?y), inc(s(+(?x_3,?y))) = +(inc(s(?x_3)),?y), inc(+(?y,?x)) = +(inc(?x),?y) ] unknown Okui (Simultaneous CPs) unknown Strongly Depth-Preserving & Root-E-Closed/Non-E-Overlapping unknown Strongly Weight-Preserving & Root-E-Closed/Non-E-Overlapping check Locally Decreasing Diagrams by Rule Labelling... Critical Pair by Rules <0, 4> preceded by [(inc,1)] joinable by a reduction of rules <[([],2)], [([(+,1)],2),([],1),([(s,1)],0)]> Critical Pair by Rules <1, 4> preceded by [(inc,1)] joinable by a reduction of rules <[([],2)], [([(+,1)],2),([],1),([(s,1)],1)]> joinable by a reduction of rules <[([(inc,1),(s,1)],3),([],2),([(s,1),(s,1)],3)], [([(+,1)],2),([],1),([(s,1)],1)]> Critical Pair by Rules <3, 4> preceded by [(inc,1)] joinable by a reduction of rules <[([(inc,1)],3),([],4)], []> joinable by a reduction of rules <[([(inc,1)],3),([],2)], [([(+,1)],2),([],1)]> joinable by a reduction of rules <[([],2),([(s,1)],3)], [([(+,1)],2),([],1)]> Critical Pair <+(?y_3,0), ?y_3> by Rules <3, 0> preceded by [] joinable by a reduction of rules <[([],3),([],0)], []> Critical Pair <+(?y_3,s(?x_1)), s(+(?x_1,?y_3))> by Rules <3, 1> preceded by [] joinable by a reduction of rules <[([],3),([],1)], []> Critical Pair <+(inc(?x_4),?y_4), s(+(?x_4,?y_4))> by Rules <4, 2> preceded by [] joinable by a reduction of rules <[([(+,1)],2),([],1)], []> unknown Diagram Decreasing check Non-Confluence... obtain 15 rules by 3 steps unfolding strenghten +(?x_8,0) and ?x_8 strenghten +(0,?x_6) and ?x_6 strenghten +(?x_11,?y_11) and +(?y_11,?x_11) strenghten s(s(?x_2)) and inc(s(?x_2)) strenghten s(inc(?x_14)) and s(s(?x_14)) strenghten +(inc(?x_6),0) and inc(?x_6) strenghten +(inc(0),?x_8) and inc(?x_8) strenghten s(+(?x_1,0)) and s(?x_1) strenghten +(inc(?x_3),?y_3) and inc(+(?y_3,?x_3)) strenghten +(inc(?x_4),?y_4) and s(+(?x_4,?y_4)) strenghten +(inc(?x_10),?y_10) and inc(+(?x_10,?y_10)) strenghten s(+(?x_1,?x_12)) and +(?x_12,s(?x_1)) strenghten s(+(?x_1,?x_13)) and +(s(?x_1),?x_13) strenghten s(+(?x_4,?y_4)) and +(inc(?x_4),?y_4) strenghten s(s(inc(?x))) and inc(s(s(?x))) strenghten +(inc(s(?x_1)),?y_1) and inc(s(+(?x_1,?y_1))) strenghten s(s(+(?x_4,?y_4))) and inc(+(inc(?x_4),?y_4)) obtain 100 candidates for checking non-joinability check by TCAP-Approximation (failure) check by Root-Approximation (failure) check by Ordering(rpo), check by Tree-Automata Approximation (failure) check by Interpretation(mod2) (failure) check by Descendants-Approximation, check by Ordering(poly) (failure) unknown Non-Confluence Check relative termination: [ +(0,?y) -> ?y, +(s(?x),?y) -> s(+(?x,?y)), inc(?x) -> s(?x), inc(+(?x,?y)) -> +(inc(?x),?y) ] [ +(?x,?y) -> +(?y,?x) ] Polynomial Interpretation: +:= (2)*x1+(2)*x2 0:= (9) s:= (1)*x1 inc:= (3)+(3)*x1+(2)*x1*x1 retract +(0,?y) -> ?y retract inc(?x) -> s(?x) Polynomial Interpretation: +:= (2)*x1+(1)*x1*x2+(2)*x2 0:= (9) s:= (6)+(4)*x1 inc:= (1)+(3)*x1+(2)*x1*x1 retract +(0,?y) -> ?y retract +(s(?x),?y) -> s(+(?x,?y)) retract inc(?x) -> s(?x) Polynomial Interpretation: +:= (1)+(1)*x1+(1)*x2 0:= (11) s:= (2)+(2)*x1+(6)*x1*x1 inc:= (4)*x1*x1 relatively terminating unknown Huet (modulo AC) check by Reduction-Preserving Completion... STEP: 1 (parallel) S: [ +(0,?y) -> ?y, +(s(?x),?y) -> s(+(?x,?y)), inc(?x) -> s(?x), inc(+(?x,?y)) -> +(inc(?x),?y) ] P: [ +(?x,?y) -> +(?y,?x) ] S: terminating CP(S,S): <+(inc(?x_3),?y_3), s(+(?x_3,?y_3))> --> => yes --> => yes --> => yes PCP_in(symP,S): --> => yes CP(S,symP): --> => no --> => no check joinability condition: check modulo reachablity from ?y to +(?y,0): maybe not reachable check modulo reachablity from s(+(?x,?y)) to +(?y,s(?x)): maybe not reachable failed failure(Step 1) [ +(?y,0) -> ?y, +(?y,s(?x)) -> s(+(?x,?y)) ] Added S-Rules: [ +(?y,0) -> ?y, +(?y,s(?x)) -> s(+(?x,?y)) ] Added P-Rules: [ ] replace: +(s(?x),?y) -> s(+(?x,?y)) => +(s(?x),?y) -> s(+(?y,?x)) STEP: 2 (linear) S: [ +(0,?y) -> ?y, +(s(?x),?y) -> s(+(?x,?y)), inc(?x) -> s(?x), inc(+(?x,?y)) -> +(inc(?x),?y) ] P: [ +(?x,?y) -> +(?y,?x) ] S: terminating CP(S,S): <+(inc(?x_3),?y_3), s(+(?x_3,?y_3))> --> => yes --> => yes --> => yes CP_in(symP,S): --> => yes CP(S,symP): --> => no --> => no check joinability condition: check modulo reachablity from ?y to +(?y,0): maybe not reachable check modulo reachablity from s(+(?x,?y)) to +(?y,s(?x)): maybe not reachable failed failure(Step 2) [ +(?y,0) -> ?y, +(?y,s(?x)) -> s(+(?x,?y)) ] Added S-Rules: [ +(?y,0) -> ?y, +(?y,s(?x)) -> s(+(?x,?y)) ] Added P-Rules: [ ] replace: +(s(?x),?y) -> s(+(?x,?y)) => +(s(?x),?y) -> s(+(?y,?x)) STEP: 3 (relative) S: [ +(0,?y) -> ?y, +(s(?x),?y) -> s(+(?x,?y)), inc(?x) -> s(?x), inc(+(?x,?y)) -> +(inc(?x),?y) ] P: [ +(?x,?y) -> +(?y,?x) ] Check relative termination: [ +(0,?y) -> ?y, +(s(?x),?y) -> s(+(?x,?y)), inc(?x) -> s(?x), inc(+(?x,?y)) -> +(inc(?x),?y) ] [ +(?x,?y) -> +(?y,?x) ] Polynomial Interpretation: +:= (2)*x1+(2)*x2 0:= (9) s:= (1)*x1 inc:= (3)+(3)*x1+(2)*x1*x1 retract +(0,?y) -> ?y retract inc(?x) -> s(?x) Polynomial Interpretation: +:= (2)*x1+(1)*x1*x2+(2)*x2 0:= (9) s:= (6)+(4)*x1 inc:= (1)+(3)*x1+(2)*x1*x1 retract +(0,?y) -> ?y retract +(s(?x),?y) -> s(+(?x,?y)) retract inc(?x) -> s(?x) Polynomial Interpretation: +:= (1)+(1)*x1+(1)*x2 0:= (11) s:= (2)+(2)*x1+(6)*x1*x1 inc:= (4)*x1*x1 relatively terminating S/P: relatively terminating check CP condition: failed failure(Step 3) STEP: 4 (parallel) S: [ +(0,?y) -> ?y, +(s(?x),?y) -> s(+(?x,?y)), inc(?x) -> s(?x), inc(+(?x,?y)) -> +(inc(?x),?y), +(?y,0) -> ?y, +(?y,s(?x)) -> s(+(?x,?y)) ] P: [ +(?x,?y) -> +(?y,?x) ] S: terminating CP(S,S): <0, 0> --> <0, 0> => yes --> => yes --> => yes --> => yes <+(inc(?x_3),?y_3), s(+(?x_3,?y_3))> --> => yes --> => yes --> => yes --> => yes --> => yes PCP_in(symP,S): --> => yes CP(S,symP): --> => yes --> => yes --> => yes --> => yes S: [ +(0,?y) -> ?y, +(s(?x),?y) -> s(+(?x,?y)), inc(?x) -> s(?x), inc(+(?x,?y)) -> +(inc(?x),?y), +(?y,0) -> ?y, +(?y,s(?x)) -> s(+(?x,?y)) ] P: [ +(?x,?y) -> +(?y,?x) ] Success Reduction-Preserving Completion Direct Methods: CR Final result: CR 141.trs: Success(CR) (1465 msec.)