Description: Define the symmetric difference of two classes. Alternate definitions are dfsymdif2 , dfsymdif3 and dfsymdif4 . (Contributed by Scott Fenton, 31-Mar-2012)
Ref | Expression | ||
---|---|---|---|
Assertion | df-symdif | |- ( A /_\ B ) = ( ( A \ B ) u. ( B \ A ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
0 | cA | |- A |
|
1 | cB | |- B |
|
2 | 0 1 | csymdif | |- ( A /_\ B ) |
3 | 0 1 | cdif | |- ( A \ B ) |
4 | 1 0 | cdif | |- ( B \ A ) |
5 | 3 4 | cun | |- ( ( A \ B ) u. ( B \ A ) ) |
6 | 2 5 | wceq | |- ( A /_\ B ) = ( ( A \ B ) u. ( B \ A ) ) |