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Theorem axi9 2730
Description: Axiom of existence (intuitionistic logic axiom ax-i9). In classical logic, this is equivalent to ax-6 2000 but in intuitionistic logic it needs to be stated using the existential quantifier. (Contributed by Jim Kingdon, 31-Dec-2017.) (New usage is discouraged.)
Assertion
Ref Expression
axi9 𝑥 𝑥 = 𝑦

Proof of Theorem axi9
StepHypRef Expression
1 ax6e 2414 1 𝑥 𝑥 = 𝑦
Colors of variables:    wff setvar class
This proof depends on syntax axioms:  wex 1812
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-12 2215  ax-13 2403
This proof depends on definitions:  df-bi 210  df-an 402  df-ex 1813
This theorem is used by: (None)
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