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Description: Consequence of filssufilg : a set whose double powerset is well-orderable satisfies the ultrafilter lemma. (Contributed by Mario Carneiro, 26-Aug-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | numufl | |- ( ~P ~P X e. dom card -> X e. UFL ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | filssufilg | |- ( ( f e. ( Fil ` X ) /\ ~P ~P X e. dom card ) -> E. g e. ( UFil ` X ) f C_ g ) |
|
| 2 | 1 | ancoms | |- ( ( ~P ~P X e. dom card /\ f e. ( Fil ` X ) ) -> E. g e. ( UFil ` X ) f C_ g ) |
| 3 | 2 | ralrimiva | |- ( ~P ~P X e. dom card -> A. f e. ( Fil ` X ) E. g e. ( UFil ` X ) f C_ g ) |
| 4 | pwexr | |- ( ~P ~P X e. dom card -> ~P X e. _V ) |
|
| 5 | pwexb | |- ( X e. _V <-> ~P X e. _V ) |
|
| 6 | 4 5 | sylibr | |- ( ~P ~P X e. dom card -> X e. _V ) |
| 7 | isufl | |- ( X e. _V -> ( X e. UFL <-> A. f e. ( Fil ` X ) E. g e. ( UFil ` X ) f C_ g ) ) |
|
| 8 | 6 7 | syl | |- ( ~P ~P X e. dom card -> ( X e. UFL <-> A. f e. ( Fil ` X ) E. g e. ( UFil ` X ) f C_ g ) ) |
| 9 | 3 8 | mpbird | |- ( ~P ~P X e. dom card -> X e. UFL ) |