Description: Closure of the bra function. (Contributed by NM, 23-May-2006) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bracl | |- ( ( A e. ~H /\ B e. ~H ) -> ( ( bra ` A ) ` B ) e. CC ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | brafn | |- ( A e. ~H -> ( bra ` A ) : ~H --> CC ) | |
| 2 | 1 | ffvelcdmda | |- ( ( A e. ~H /\ B e. ~H ) -> ( ( bra ` A ) ` B ) e. CC ) |