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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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