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Description: The characteristic of a ring is the smallest positive integer which is equal to 0 when interpreted in the ring, or 0 if there is no such positive integer. (Contributed by Stefan O'Rear, 5-Sep-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-chr | ⊢ chr = ( 𝑔 ∈ V ↦ ( ( od ‘ 𝑔 ) ‘ ( 1r ‘ 𝑔 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cchr | ⊢ chr | |
| 1 | vg | ⊢ 𝑔 | |
| 2 | cvv | ⊢ V | |
| 3 | cod | ⊢ od | |
| 4 | 1 | cv | ⊢ 𝑔 |
| 5 | 4 3 | cfv | ⊢ ( od ‘ 𝑔 ) |
| 6 | cur | ⊢ 1r | |
| 7 | 4 6 | cfv | ⊢ ( 1r ‘ 𝑔 ) |
| 8 | 7 5 | cfv | ⊢ ( ( od ‘ 𝑔 ) ‘ ( 1r ‘ 𝑔 ) ) |
| 9 | 1 2 8 | cmpt | ⊢ ( 𝑔 ∈ V ↦ ( ( od ‘ 𝑔 ) ‘ ( 1r ‘ 𝑔 ) ) ) |
| 10 | 0 9 | wceq | ⊢ chr = ( 𝑔 ∈ V ↦ ( ( od ‘ 𝑔 ) ‘ ( 1r ‘ 𝑔 ) ) ) |