Theorem equcomiv 2018

Description: Weaker form of equcomi 2021 with a disjoint variable condition on 𝑥, 𝑦. This is an intermediate step and equcomi 2021 is fully recovered later. (Contributed by BJ, 7-Dec-2020.)

Assertion

Ref	Expression
equcomiv	⊢ (𝑥 = 𝑦 → 𝑦 = 𝑥)

Distinct variable group:   𝑥,𝑦

Proof of Theorem equcomiv

Step	Hyp	Ref	Expression
1		equid 2016	. 2 ⊢ 𝑥 = 𝑥
2		ax7v2 2015	. 2 ⊢ (𝑥 = 𝑦 → (𝑥 = 𝑥 → 𝑦 = 𝑥))
3	1, 2	mpi 20	1 ⊢ (𝑥 = 𝑦 → 𝑦 = 𝑥)

Syntax hints:   → wi 4

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1799  ax-4 1813  ax-5 1914  ax-6 1972  ax-7 2012

This theorem depends on definitions:  df-bi 206  df-ex 1784

This theorem is referenced by:  ax6evr  2019