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| Description: 1 is a complex number. Axiom 3 of 25 for real and complex numbers, derived from ZF set theory. |
| Ref | Expression |
|---|---|
| ax1cn |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | axresscn 5333 |
. 2
| |
| 2 | df-1 5307 |
. . 3
| |
| 3 | 1r 5255 |
. . . 4
| |
| 4 | opelreal 5314 |
. . . 4
| |
| 5 | 3, 4 | mpbir 197 |
. . 3
|
| 6 | 2, 5 | eqeltri 1591 |
. 2
|
| 7 | 1, 6 | sselii 2117 |
1
|