Metamath Proof Explorer


Theorem funressneu

Description: There is exactly one value of a class which is a function restricted to a singleton, analogous to funeu . A e. _V is required because otherwise E! y A F y , see brprcneu . (Contributed by AV, 7-Sep-2022)

Ref Expression
Assertion funressneu
|- ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> E! y A F y )

Proof

Step Hyp Ref Expression
1 simp1l
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> A e. V )
2 simp1r
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> B e. W )
3 simp3
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> A F B )
4 breldmg
 |-  ( ( A e. V /\ B e. W /\ A F B ) -> A e. dom F )
5 1 2 3 4 syl3anc
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> A e. dom F )
6 eldmg
 |-  ( A e. dom F -> ( A e. dom F <-> E. y A F y ) )
7 6 ibi
 |-  ( A e. dom F -> E. y A F y )
8 5 7 syl
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> E. y A F y )
9 simpl
 |-  ( ( A e. V /\ B e. W ) -> A e. V )
10 9 anim1i
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) ) -> ( A e. V /\ Fun ( F |` { A } ) ) )
11 10 3adant3
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> ( A e. V /\ Fun ( F |` { A } ) ) )
12 funressnmo
 |-  ( ( A e. V /\ Fun ( F |` { A } ) ) -> E* y A F y )
13 11 12 syl
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> E* y A F y )
14 moeu
 |-  ( E* y A F y <-> ( E. y A F y -> E! y A F y ) )
15 13 14 sylib
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> ( E. y A F y -> E! y A F y ) )
16 8 15 mpd
 |-  ( ( ( A e. V /\ B e. W ) /\ Fun ( F |` { A } ) /\ A F B ) -> E! y A F y )