| 1: | p(0) | → 0 | |
| 2: | p(s(x)) | → x | |
| 3: | le(0,y) | → true | |
| 4: | le(s(x),0) | → false | |
| 5: | le(s(x),s(y)) | → le(x,y) | |
| 6: | minus(x,0) | → x | |
| 7: | minus(x,s(y)) | → if(le(x,s(y)),0,p(minus(x,p(s(y))))) | |
| 8: | if(true,x,y) | → x | |
| 9: | if(false,x,y) | → y | |
| 10: | LE(s(x),s(y)) | → LE(x,y) | |
| 11: | MINUS(x,s(y)) | → IF(le(x,s(y)),0,p(minus(x,p(s(y))))) | |
| 12: | MINUS(x,s(y)) | → LE(x,s(y)) | |
| 13: | MINUS(x,s(y)) | → P(minus(x,p(s(y)))) | |
| 14: | MINUS(x,s(y)) | → MINUS(x,p(s(y))) | |
| 15: | MINUS(x,s(y)) | → P(s(y)) | |