Description: Alternate proof of vtocl . Shorter but requires more axioms. (Contributed by NM, 30-Aug-1993) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | vtocl.1 | |- A e. _V |
|
| vtocl.2 | |- ( x = A -> ( ph <-> ps ) ) |
||
| vtocl.3 | |- ph |
||
| Assertion | vtoclALT | |- ps |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | vtocl.1 | |- A e. _V |
|
| 2 | vtocl.2 | |- ( x = A -> ( ph <-> ps ) ) |
|
| 3 | vtocl.3 | |- ph |
|
| 4 | nfv | |- F/ x ps |
|
| 5 | 4 1 2 3 | vtoclf | |- ps |