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Theorem axi9 2784
Description: Axiom of existence (intuitionistic logic axiom ax-i9). In classical logic, this is equivalent to ax-6 1961 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 2392 1 𝑥 𝑥 = 𝑦
Colors of variables: wff setvar class
Syntax hints:  wex 1771
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1787  ax-4 1801  ax-5 1902  ax-6 1961  ax-7 2006  ax-12 2167  ax-13 2381
This theorem depends on definitions:  df-bi 208  df-an 397  df-ex 1772
This theorem is referenced by: (None)
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