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| Mirrors > Home > MPE Home > Th. List > 1nn | Structured version Visualization version Unicode version | ||
| Description: Peano postulate: 1 is a positive integer. (Contributed by NM, 11-Jan-1997.) (Revised by Mario Carneiro, 17-Nov-2014.) |
| Ref | Expression |
|---|---|
| 1nn |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 1ex 10035 |
. . . 4
| |
| 2 | fr0g 7531 |
. . . 4
| |
| 3 | 1, 2 | ax-mp 5 |
. . 3
|
| 4 | frfnom 7530 |
. . . 4
| |
| 5 | peano1 7085 |
. . . 4
| |
| 6 | fnfvelrn 6356 |
. . . 4
| |
| 7 | 4, 5, 6 | mp2an 708 |
. . 3
|
| 8 | 3, 7 | eqeltrri 2698 |
. 2
|
| 9 | df-nn 11021 |
. . 3
| |
| 10 | df-ima 5127 |
. . 3
| |
| 11 | 9, 10 | eqtri 2644 |
. 2
|
| 12 | 8, 11 | eleqtrri 2700 |
1
|
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