Theorem frege54cor1b

Description: Reflexive equality. (Contributed by RP, 24-Dec-2019)

	Ref	Expression
Assertion	frege54cor1b	⊢ [ 𝑥 / 𝑦 ] 𝑦 = 𝑥

Proof

Step	Hyp	Ref	Expression
1		equsb1	⊢ [ 𝑥 / 𝑦 ] 𝑦 = 𝑥