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Description: The zero function is a polynomial. (Contributed by Mario Carneiro, 17-Jul-2014)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | ply0 | ⊢ ( 𝑆 ⊆ ℂ → 0𝑝 ∈ ( Poly ‘ 𝑆 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-0p | ⊢ 0𝑝 = ( ℂ × { 0 } ) | |
| 2 | id | ⊢ ( 𝑆 ⊆ ℂ → 𝑆 ⊆ ℂ ) | |
| 3 | 0cnd | ⊢ ( 𝑆 ⊆ ℂ → 0 ∈ ℂ ) | |
| 4 | 3 | snssd | ⊢ ( 𝑆 ⊆ ℂ → { 0 } ⊆ ℂ ) |
| 5 | 2 4 | unssd | ⊢ ( 𝑆 ⊆ ℂ → ( 𝑆 ∪ { 0 } ) ⊆ ℂ ) |
| 6 | ssun2 | ⊢ { 0 } ⊆ ( 𝑆 ∪ { 0 } ) | |
| 7 | c0ex | ⊢ 0 ∈ V | |
| 8 | 7 | snss | ⊢ ( 0 ∈ ( 𝑆 ∪ { 0 } ) ↔ { 0 } ⊆ ( 𝑆 ∪ { 0 } ) ) |
| 9 | 6 8 | mpbir | ⊢ 0 ∈ ( 𝑆 ∪ { 0 } ) |
| 10 | plyconst | ⊢ ( ( ( 𝑆 ∪ { 0 } ) ⊆ ℂ ∧ 0 ∈ ( 𝑆 ∪ { 0 } ) ) → ( ℂ × { 0 } ) ∈ ( Poly ‘ ( 𝑆 ∪ { 0 } ) ) ) | |
| 11 | 5 9 10 | sylancl | ⊢ ( 𝑆 ⊆ ℂ → ( ℂ × { 0 } ) ∈ ( Poly ‘ ( 𝑆 ∪ { 0 } ) ) ) |
| 12 | 1 11 | eqeltrid | ⊢ ( 𝑆 ⊆ ℂ → 0𝑝 ∈ ( Poly ‘ ( 𝑆 ∪ { 0 } ) ) ) |
| 13 | plyun0 | ⊢ ( Poly ‘ ( 𝑆 ∪ { 0 } ) ) = ( Poly ‘ 𝑆 ) | |
| 14 | 12 13 | eleqtrdi | ⊢ ( 𝑆 ⊆ ℂ → 0𝑝 ∈ ( Poly ‘ 𝑆 ) ) |