Metamath Proof Explorer


Theorem membpartlem19

Description: Together with disjlem19 , this is former prtlem19 . (Contributed by Rodolfo Medina, 15-Oct-2010) (Revised by Mario Carneiro, 12-Aug-2015) (Revised by Peter Mazsa, 21-Oct-2021)

Ref Expression
Assertion membpartlem19 B V MembPart A u A B u u = B A

Proof

Step Hyp Ref Expression
1 dfmembpart2 MembPart A ElDisj A ¬ A
2 n0el2 ¬ A dom E -1 A = A
3 2 biimpi ¬ A dom E -1 A = A
4 3 ad2antll B V ElDisj A ¬ A dom E -1 A = A
5 4 eleq2d B V ElDisj A ¬ A u dom E -1 A u A
6 eldisjlem19 B V ElDisj A u dom E -1 A B u u = B A
7 6 adantrd B V ElDisj A ¬ A u dom E -1 A B u u = B A
8 7 imp B V ElDisj A ¬ A u dom E -1 A B u u = B A
9 8 expd B V ElDisj A ¬ A u dom E -1 A B u u = B A
10 5 9 sylbird B V ElDisj A ¬ A u A B u u = B A
11 1 10 sylan2b B V MembPart A u A B u u = B A
12 11 impd B V MembPart A u A B u u = B A
13 12 ex B V MembPart A u A B u u = B A