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Metamath Proof Explorer


Theorem eqab

Description: One direction of eqabb is provable from fewer axioms. (Contributed by Wolf Lammen, 13-Feb-2025)

Ref Expression
Assertion eqab x x A φ A = x | φ

Proof

Step Hyp Ref Expression
1 abid1 A = x | x A
2 abbi x x A φ x | x A = x | φ
3 1 2 eqtrid x x A φ A = x | φ