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| Mirrors > Home > NFE Home > Th. List > axi9 | GIF version | ||
| Description: Axiom of existence (intuitionistic logic axiom ax-i9). In classical logic, this is equivalent to ax-9 1654 but in intuitionistic logic it needs to be stated using the existential quantifier. (Contributed by Jim Kingdon, 31-Dec-2017.) |
| Ref | Expression |
|---|---|
| axi9 | ⊢ ∃x x = y |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | a9e 1951 | 1 ⊢ ∃x x = y |
| Colors of variables: wff setvar class |
| Syntax hints: ∃wex 1541 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1546 ax-5 1557 ax-17 1616 ax-9 1654 ax-8 1675 ax-6 1729 ax-7 1734 ax-11 1746 ax-12 1925 |
| This theorem depends on definitions: df-bi 177 df-an 360 df-tru 1319 df-ex 1542 df-nf 1545 |
| This theorem is referenced by: (None) |
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