Metamath Proof Explorer


Theorem intrnfi

Description: Sufficient condition for the intersection of the range of a function to be in the set of finite intersections. (Contributed by Mario Carneiro, 30-Aug-2015)

Ref Expression
Assertion intrnfi B V F : A B A A Fin ran F fi B

Proof

Step Hyp Ref Expression
1 simpr1 B V F : A B A A Fin F : A B
2 1 frnd B V F : A B A A Fin ran F B
3 1 fdmd B V F : A B A A Fin dom F = A
4 simpr2 B V F : A B A A Fin A
5 3 4 eqnetrd B V F : A B A A Fin dom F
6 dm0rn0 dom F = ran F =
7 6 necon3bii dom F ran F
8 5 7 sylib B V F : A B A A Fin ran F
9 simpr3 B V F : A B A A Fin A Fin
10 1 ffnd B V F : A B A A Fin F Fn A
11 dffn4 F Fn A F : A onto ran F
12 10 11 sylib B V F : A B A A Fin F : A onto ran F
13 fofi A Fin F : A onto ran F ran F Fin
14 9 12 13 syl2anc B V F : A B A A Fin ran F Fin
15 2 8 14 3jca B V F : A B A A Fin ran F B ran F ran F Fin
16 elfir B V ran F B ran F ran F Fin ran F fi B
17 15 16 syldan B V F : A B A A Fin ran F fi B