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Description: The unity element of the field of reals. (Contributed by Thierry Arnoux, 1-Nov-2017)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | re1r | ⊢ 1 = ( 1r ‘ ℝfld ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | resubdrg | ⊢ ( ℝ ∈ ( SubRing ‘ ℂfld ) ∧ ℝfld ∈ DivRing ) | |
| 2 | 1 | simpli | ⊢ ℝ ∈ ( SubRing ‘ ℂfld ) |
| 3 | df-refld | ⊢ ℝfld = ( ℂfld ↾s ℝ ) | |
| 4 | cnfld1 | ⊢ 1 = ( 1r ‘ ℂfld ) | |
| 5 | 3 4 | subrg1 | ⊢ ( ℝ ∈ ( SubRing ‘ ℂfld ) → 1 = ( 1r ‘ ℝfld ) ) |
| 6 | 2 5 | ax-mp | ⊢ 1 = ( 1r ‘ ℝfld ) |