Metamath Proof Explorer


Theorem alephdom2

Description: A dominated initial ordinal is included. (Contributed by Jeff Hankins, 24-Oct-2009)

Ref Expression
Assertion alephdom2 A On B On A B A B

Proof

Step Hyp Ref Expression
1 alephsdom B On A On B A B A
2 1 ancoms A On B On B A B A
3 2 notbid A On B On ¬ B A ¬ B A
4 alephon A On
5 4 onordi Ord A
6 eloni B On Ord B
7 ordtri1 Ord A Ord B A B ¬ B A
8 5 6 7 sylancr B On A B ¬ B A
9 8 adantl A On B On A B ¬ B A
10 domtriord A On B On A B ¬ B A
11 4 10 mpan B On A B ¬ B A
12 11 adantl A On B On A B ¬ B A
13 3 9 12 3bitr4d A On B On A B A B