Metamath Proof Explorer
Description: Alternate version of sb1 . (Contributed by NM, 13-May-1993)
(Proof modification is discouraged.) (New usage is discouraged.)
|
|
Ref |
Expression |
|
Hypothesis |
dfsb1.ph |
|
|
Assertion |
sb1ALT |
|
Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
dfsb1.ph |
|
2 |
1
|
simprbi |
|