Description: Deduction adding a right disjunct to both sides of a logical equivalence. (Contributed by NM, 21-Jun-1993)
Ref | Expression | ||
---|---|---|---|
Hypothesis | bid.1 | |
|
Assertion | orbi1d | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | bid.1 | |
|
2 | 1 | orbi2d | |
3 | orcom | |
|
4 | orcom | |
|
5 | 2 3 4 | 3bitr4g | |