Theorem equcomi1 36030

Description: Proof of equcomi 2020 from equid1 36029, avoiding use of ax-5 1907 (the only use of ax-5 1907 is via ax7 2019, so using ax-7 2011 instead would remove dependency on ax-5 1907). (Contributed by BJ, 8-Jul-2021.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
equcomi1	⊢ (𝑥 = 𝑦 → 𝑦 = 𝑥)

Proof of Theorem equcomi1

Step	Hyp	Ref	Expression
1		equid1 36029	. 2 ⊢ 𝑥 = 𝑥
2		ax7 2019	. 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 1792  ax-4 1806  ax-5 1907  ax-6 1966  ax-7 2011  ax-c5 36013  ax-c4 36014  ax-c7 36015  ax-c10 36016  ax-c9 36020

This theorem depends on definitions:  df-bi 209  df-an 399  df-ex 1777

This theorem is referenced by:  aecom-o  36031