2. r: Term
3. t': Term
4. r': Term
5. t
= t'6. r
= r'
SUBX(t; r) = SUBX(t'; r')
t,r,t',r':Term. t = t' & r = r' 
SUBX(t; r) = SUBX(t'; r')
| 1 | 1. t: Term 2. r: Term 3. t': Term 4. r': Term 5. t = t'6. r = r' SUBX(t; r) = SUBX(t'; r') | 6 steps |
About:
 |  |  |