| 1: | minus(x,0) | → x | |
| 2: | minus(s(x),s(y)) | → minus(x,y) | |
| 3: | double(0) | → 0 | |
| 4: | double(s(x)) | → s(s(double(x))) | |
| 5: | plus(0,y) | → y | |
| 6: | plus(s(x),y) | → s(plus(x,y)) | |
| 7: | plus(s(x),y) | → plus(x,s(y)) | |
| 8: | plus(s(x),y) | → s(plus(minus(x,y),double(y))) | |
| 9: | plus(s(plus(x,y)),z) | → s(plus(plus(x,y),z)) | |
| 10: | MINUS(s(x),s(y)) | → MINUS(x,y) | |
| 11: | DOUBLE(s(x)) | → DOUBLE(x) | |
| 12: | PLUS(s(x),y) | → PLUS(x,y) | |
| 13: | PLUS(s(x),y) | → PLUS(x,s(y)) | |
| 14: | PLUS(s(x),y) | → PLUS(minus(x,y),double(y)) | |
| 15: | PLUS(s(x),y) | → MINUS(x,y) | |
| 16: | PLUS(s(x),y) | → DOUBLE(y) | |
| 17: | PLUS(s(plus(x,y)),z) | → PLUS(plus(x,y),z) | |