Description: Adding a superfluous conjunct in a biconditional. (Contributed by Thierry Arnoux, 26-Feb-2017)
Ref | Expression | ||
---|---|---|---|
Hypothesis | bian1d.1 | |
|
Assertion | bian1d | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | bian1d.1 | |
|
2 | 1 | biimpd | |
3 | 2 | adantld | |
4 | simpl | |
|
5 | 4 | a1i | |
6 | 1 | biimprd | |
7 | 5 6 | jcad | |
8 | 3 7 | impbid | |