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Theorem axi9 2598
Description: Axiom of existence (intuitionistic logic axiom ax-i9). In classical logic, this is equivalent to ax-6 1888 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  |-  E. x  x  =  y

Proof of Theorem axi9
StepHypRef Expression
1 ax6e 2250 1  |-  E. x  x  =  y
Colors of variables: wff setvar class
Syntax hints:   E.wex 1704
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-12 2047  ax-13 2246
This theorem depends on definitions:  df-bi 197  df-an 386  df-ex 1705
This theorem is referenced by: (None)
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