Description: Lemma for bcxmas . (Contributed by Paul Chapman, 18-May-2007)
Ref | Expression | ||
---|---|---|---|
Assertion | bcxmaslem1 | |- ( A = B -> ( ( N + A ) _C A ) = ( ( N + B ) _C B ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | oveq2 | |- ( A = B -> ( N + A ) = ( N + B ) ) |
|
2 | id | |- ( A = B -> A = B ) |
|
3 | 1 2 | oveq12d | |- ( A = B -> ( ( N + A ) _C A ) = ( ( N + B ) _C B ) ) |