Metamath Proof Explorer


Theorem predonOLD

Description: Obsolete version of predon as of 16-Oct-2024. (Contributed by Scott Fenton, 27-Mar-2011) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Assertion predonOLD
|- ( A e. On -> Pred ( _E , On , A ) = A )

Proof

Step Hyp Ref Expression
1 predep
 |-  ( A e. On -> Pred ( _E , On , A ) = ( On i^i A ) )
2 onss
 |-  ( A e. On -> A C_ On )
3 sseqin2
 |-  ( A C_ On <-> ( On i^i A ) = A )
4 2 3 sylib
 |-  ( A e. On -> ( On i^i A ) = A )
5 1 4 eqtrd
 |-  ( A e. On -> Pred ( _E , On , A ) = A )