(VAR x y z) (RULES p(s(x)) -> x s(p(x)) -> x +(0,y) -> y +(s(x),y) -> s(+(x,y)) +(p(x),y) -> p(+(x,y)) minus(0) -> 0 minus(s(x)) -> p(minus(x)) minus(p(x)) -> s(minus(x)) *(0,y) -> 0 *(s(x),y) -> +(*(x,y),y) *(p(x),y) -> +(*(x,y),minus(y)) ) (COMMENT Example 4.14 in \cite{SK90})