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Description: A transitive Tarski class is closed under small unions. (Contributed by Mario Carneiro, 22-Jun-2013)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | tskurn | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> U. ran F e. T ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | simp1l | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> T e. Tarski ) |
|
| 2 | simp1r | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> Tr T ) |
|
| 3 | frn | |- ( F : A --> T -> ran F C_ T ) |
|
| 4 | 3 | 3ad2ant3 | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> ran F C_ T ) |
| 5 | tskwe2 | |- ( T e. Tarski -> T e. dom card ) |
|
| 6 | 1 5 | syl | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> T e. dom card ) |
| 7 | simp2 | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> A e. T ) |
|
| 8 | trss | |- ( Tr T -> ( A e. T -> A C_ T ) ) |
|
| 9 | 2 7 8 | sylc | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> A C_ T ) |
| 10 | ssnum | |- ( ( T e. dom card /\ A C_ T ) -> A e. dom card ) |
|
| 11 | 6 9 10 | syl2anc | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> A e. dom card ) |
| 12 | ffn | |- ( F : A --> T -> F Fn A ) |
|
| 13 | dffn4 | |- ( F Fn A <-> F : A -onto-> ran F ) |
|
| 14 | 12 13 | sylib | |- ( F : A --> T -> F : A -onto-> ran F ) |
| 15 | 14 | 3ad2ant3 | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> F : A -onto-> ran F ) |
| 16 | fodomnum | |- ( A e. dom card -> ( F : A -onto-> ran F -> ran F ~<_ A ) ) |
|
| 17 | 11 15 16 | sylc | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> ran F ~<_ A ) |
| 18 | tsksdom | |- ( ( T e. Tarski /\ A e. T ) -> A ~< T ) |
|
| 19 | 1 7 18 | syl2anc | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> A ~< T ) |
| 20 | domsdomtr | |- ( ( ran F ~<_ A /\ A ~< T ) -> ran F ~< T ) |
|
| 21 | 17 19 20 | syl2anc | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> ran F ~< T ) |
| 22 | tskssel | |- ( ( T e. Tarski /\ ran F C_ T /\ ran F ~< T ) -> ran F e. T ) |
|
| 23 | 1 4 21 22 | syl3anc | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> ran F e. T ) |
| 24 | tskuni | |- ( ( T e. Tarski /\ Tr T /\ ran F e. T ) -> U. ran F e. T ) |
|
| 25 | 1 2 23 24 | syl3anc | |- ( ( ( T e. Tarski /\ Tr T ) /\ A e. T /\ F : A --> T ) -> U. ran F e. T ) |