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Description: A nonzero univariate polynomial over a domain always has a nonzero-divisor leading coefficient. (Contributed by Stefan O'Rear, 28-Mar-2015)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | deg1z.d | ⊢ 𝐷 = ( deg1 ‘ 𝑅 ) | |
| deg1z.p | ⊢ 𝑃 = ( Poly1 ‘ 𝑅 ) | ||
| deg1z.z | ⊢ 0 = ( 0g ‘ 𝑃 ) | ||
| deg1nn0cl.b | ⊢ 𝐵 = ( Base ‘ 𝑃 ) | ||
| deg1ldgdomn.e | ⊢ 𝐸 = ( RLReg ‘ 𝑅 ) | ||
| deg1ldgdomn.a | ⊢ 𝐴 = ( coe1 ‘ 𝐹 ) | ||
| Assertion | deg1ldgdomn | ⊢ ( ( 𝑅 ∈ Domn ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → ( 𝐴 ‘ ( 𝐷 ‘ 𝐹 ) ) ∈ 𝐸 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | deg1z.d | ⊢ 𝐷 = ( deg1 ‘ 𝑅 ) | |
| 2 | deg1z.p | ⊢ 𝑃 = ( Poly1 ‘ 𝑅 ) | |
| 3 | deg1z.z | ⊢ 0 = ( 0g ‘ 𝑃 ) | |
| 4 | deg1nn0cl.b | ⊢ 𝐵 = ( Base ‘ 𝑃 ) | |
| 5 | deg1ldgdomn.e | ⊢ 𝐸 = ( RLReg ‘ 𝑅 ) | |
| 6 | deg1ldgdomn.a | ⊢ 𝐴 = ( coe1 ‘ 𝐹 ) | |
| 7 | simp1 | ⊢ ( ( 𝑅 ∈ Domn ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → 𝑅 ∈ Domn ) | |
| 8 | eqid | ⊢ ( Base ‘ 𝑅 ) = ( Base ‘ 𝑅 ) | |
| 9 | 6 4 2 8 | coe1f | ⊢ ( 𝐹 ∈ 𝐵 → 𝐴 : ℕ0 ⟶ ( Base ‘ 𝑅 ) ) |
| 10 | 9 | 3ad2ant2 | ⊢ ( ( 𝑅 ∈ Domn ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → 𝐴 : ℕ0 ⟶ ( Base ‘ 𝑅 ) ) |
| 11 | domnring | ⊢ ( 𝑅 ∈ Domn → 𝑅 ∈ Ring ) | |
| 12 | 1 2 3 4 | deg1nn0cl | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → ( 𝐷 ‘ 𝐹 ) ∈ ℕ0 ) |
| 13 | 11 12 | syl3an1 | ⊢ ( ( 𝑅 ∈ Domn ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → ( 𝐷 ‘ 𝐹 ) ∈ ℕ0 ) |
| 14 | 10 13 | ffvelcdmd | ⊢ ( ( 𝑅 ∈ Domn ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → ( 𝐴 ‘ ( 𝐷 ‘ 𝐹 ) ) ∈ ( Base ‘ 𝑅 ) ) |
| 15 | eqid | ⊢ ( 0g ‘ 𝑅 ) = ( 0g ‘ 𝑅 ) | |
| 16 | 1 2 3 4 15 6 | deg1ldg | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → ( 𝐴 ‘ ( 𝐷 ‘ 𝐹 ) ) ≠ ( 0g ‘ 𝑅 ) ) |
| 17 | 11 16 | syl3an1 | ⊢ ( ( 𝑅 ∈ Domn ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → ( 𝐴 ‘ ( 𝐷 ‘ 𝐹 ) ) ≠ ( 0g ‘ 𝑅 ) ) |
| 18 | 8 5 15 | domnrrg | ⊢ ( ( 𝑅 ∈ Domn ∧ ( 𝐴 ‘ ( 𝐷 ‘ 𝐹 ) ) ∈ ( Base ‘ 𝑅 ) ∧ ( 𝐴 ‘ ( 𝐷 ‘ 𝐹 ) ) ≠ ( 0g ‘ 𝑅 ) ) → ( 𝐴 ‘ ( 𝐷 ‘ 𝐹 ) ) ∈ 𝐸 ) |
| 19 | 7 14 17 18 | syl3anc | ⊢ ( ( 𝑅 ∈ Domn ∧ 𝐹 ∈ 𝐵 ∧ 𝐹 ≠ 0 ) → ( 𝐴 ‘ ( 𝐷 ‘ 𝐹 ) ) ∈ 𝐸 ) |