Metamath Proof Explorer
Description: Similar to 3imp except the outermost and innermost implications are
biconditionals. (Contributed by Alan Sare, 6-Nov-2017)
|
|
Ref |
Expression |
|
Hypothesis |
bi13imp2.1 |
|
|
Assertion |
bi13imp2 |
|
Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
bi13imp2.1 |
|
2 |
1
|
biimpi |
|
3 |
2
|
bi33imp12 |
|