Metamath Proof Explorer


Theorem weeq12d

Description: Equality deduction for well-orders. (Contributed by Stefan O'Rear, 19-Jan-2015)

Ref Expression
Hypotheses weeq12d.l
|- ( ph -> R = S )
weeq12d.r
|- ( ph -> A = B )
Assertion weeq12d
|- ( ph -> ( R We A <-> S We B ) )

Proof

Step Hyp Ref Expression
1 weeq12d.l
 |-  ( ph -> R = S )
2 weeq12d.r
 |-  ( ph -> A = B )
3 weeq1
 |-  ( R = S -> ( R We A <-> S We A ) )
4 1 3 syl
 |-  ( ph -> ( R We A <-> S We A ) )
5 weeq2
 |-  ( A = B -> ( S We A <-> S We B ) )
6 2 5 syl
 |-  ( ph -> ( S We A <-> S We B ) )
7 4 6 bitrd
 |-  ( ph -> ( R We A <-> S We B ) )