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| Description: Axiom of existence (intuitionistic logic axiom ax-i9). In classical logic, this is equivalent to ax-6 1967 but in intuitionistic logic it needs to be stated using the existential quantifier. (Contributed by Jim Kingdon, 31-Dec-2017.) (New usage is discouraged.) | 
| Ref | Expression | 
|---|---|
| axi9 | ⊢ ∃𝑥 𝑥 = 𝑦 | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | ax6e 2388 | 1 ⊢ ∃𝑥 𝑥 = 𝑦 | 
| Colors of variables: wff setvar class | 
| Syntax hints: ∃wex 1779 | 
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1910 ax-6 1967 ax-7 2007 ax-12 2177 ax-13 2377 | 
| This theorem depends on definitions: df-bi 207 df-an 396 df-ex 1780 | 
| This theorem is referenced by: (None) | 
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