Sorry if aan improper question, looking into metamath and metamath-lamp and though it should be trivial to prove A = 2 -> ( A + 2 ) = 4, or the inverse.
But cant seem to get it right in metamath-lamp.
Starting with hypothesis H ( A + 2 ) = 4
it should (?) be possible, even simple, to get to:
G A = 2
Started with:
- H |- ( A + 2 ) = 4
- P 2p2e4 |- ( 2 + 2 ) = 4
- P eqtr4i |- ( A + 2 ) = ( 2 + 2 )
After this, I'm blocked, cant find the steps that get to the goal: A = 2
Wouldn't asome existing simplification with ( X F A ) = ( Y F A ) -> X = Y do the trick? Does it exists in set.mm? How do I apply it?