Description: Direction by inclusion as used here implies sethood. (Contributed by Stefan O'Rear, 2-Apr-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | ipodrscl | |- ( ( toInc ` A ) e. Dirset -> A e. _V ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | isipodrs | |- ( ( toInc ` A ) e. Dirset <-> ( A e. _V /\ A =/= (/) /\ A. x e. A A. y e. A E. z e. A ( x u. y ) C_ z ) ) |
|
| 2 | 1 | simp1bi | |- ( ( toInc ` A ) e. Dirset -> A e. _V ) |