Theorem bj-alequex 36828

Description: A fol lemma. See alequexv 2002 for a version with a disjoint variable condition requiring fewer axioms. Can be used to reduce the proof of spimt 2386 from 133 to 112 bytes. (Contributed by BJ, 6-Oct-2018.)

Assertion

Ref	Expression
bj-alequex	⊢ (∀𝑥(𝑥 = 𝑦 → 𝜑) → ∃𝑥𝜑)

Proof of Theorem bj-alequex

Step	Hyp	Ref	Expression
1		ax6e 2383	. 2 ⊢ ∃𝑥 𝑥 = 𝑦
2		exim 1835	. 2 ⊢ (∀𝑥(𝑥 = 𝑦 → 𝜑) → (∃𝑥 𝑥 = 𝑦 → ∃𝑥𝜑))
3	1, 2	mpi 20	1 ⊢ (∀𝑥(𝑥 = 𝑦 → 𝜑) → ∃𝑥𝜑)

Syntax hints:   → wi 4  ∀wal 1539  ∃wex 1780

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-12 2180  ax-13 2372

This theorem depends on definitions:  df-bi 207  df-an 396  df-ex 1781

This theorem is referenced by:  bj-spimt2  36829  bj-equsal1t  36866