YES (ignored inputs)COMMENT the following rules are removed from the original TRS + ( x , 0 ( ) ) -> x - ( 0 ( ) , 0 ( ) ) -> 0 ( ) Rewrite Rules: [ s(p(?x)) -> ?x, p(s(?x)) -> ?x, +(?x,s(?y)) -> s(+(?x,?y)), +(?x,p(?y)) -> p(+(?x,?y)), -(?x,s(?y)) -> p(-(?x,?y)), -(?x,p(?y)) -> s(-(?x,?y)), -(p(?x),?y) -> p(-(?x,?y)), -(s(?x),?y) -> s(-(?x,?y)) ] Apply Direct Methods... Inner CPs: [ s(?x_1) = s(?x_1), p(?x) = p(?x), +(?x_2,?x) = s(+(?x_2,p(?x))), +(?x_3,?x_1) = p(+(?x_3,s(?x_1))), -(?x_4,?x) = p(-(?x_4,p(?x))), -(?x_5,?x_1) = s(-(?x_5,s(?x_1))), -(?x_1,?y_6) = p(-(s(?x_1),?y_6)), -(?x,?y_7) = s(-(p(?x),?y_7)) ] Outer CPs: [ p(-(p(?x_6),?y_4)) = p(-(?x_6,s(?y_4))), p(-(s(?x_7),?y_4)) = s(-(?x_7,s(?y_4))), s(-(p(?x_6),?y_5)) = p(-(?x_6,p(?y_5))), s(-(s(?x_7),?y_5)) = s(-(?x_7,p(?y_5))) ] not Overlay, check Termination... Terminating, WCR Knuth & Bendix Direct Methods: CR Combined result: CR /tmp/filehv97n8.trs: Success(CR) (12 msec.)