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| Mirrors > Home > NFE Home > Th. List > ax-10d | GIF version | ||
| Description: Distinct variable version of ax10 1944. (Contributed by Mario Carneiro, 14-Aug-2015.) | 
| Ref | Expression | 
|---|---|
| ax-10d | ⊢ (∀x x = y → ∀y y = x) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | vx | . . . 4 setvar x | |
| 2 | vy | . . . 4 setvar y | |
| 3 | 1, 2 | weq 1643 | . . 3 wff x = y | 
| 4 | 3, 1 | wal 1540 | . 2 wff ∀x x = y | 
| 5 | 2, 1 | weq 1643 | . . 3 wff y = x | 
| 6 | 5, 2 | wal 1540 | . 2 wff ∀y y = x | 
| 7 | 4, 6 | wi 4 | 1 wff (∀x x = y → ∀y y = x) | 
| Colors of variables: wff setvar class | 
| This axiom is referenced by: (None) | 
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