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Description: The absolute value of the product of the elements of a finite subset of the integers is divisible by each element of this subset. (Contributed by AV, 21-Aug-2020)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | absproddvds.s | ⊢ ( 𝜑 → 𝑍 ⊆ ℤ ) | |
| absproddvds.f | ⊢ ( 𝜑 → 𝑍 ∈ Fin ) | ||
| absproddvds.p | ⊢ 𝑃 = ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) | ||
| Assertion | absproddvds | ⊢ ( 𝜑 → ∀ 𝑚 ∈ 𝑍 𝑚 ∥ 𝑃 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | absproddvds.s | ⊢ ( 𝜑 → 𝑍 ⊆ ℤ ) | |
| 2 | absproddvds.f | ⊢ ( 𝜑 → 𝑍 ∈ Fin ) | |
| 3 | absproddvds.p | ⊢ 𝑃 = ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) | |
| 4 | 2 1 | fproddvdsd | ⊢ ( 𝜑 → ∀ 𝑚 ∈ 𝑍 𝑚 ∥ ∏ 𝑧 ∈ 𝑍 𝑧 ) |
| 5 | 1 | sselda | ⊢ ( ( 𝜑 ∧ 𝑚 ∈ 𝑍 ) → 𝑚 ∈ ℤ ) |
| 6 | 1 | sselda | ⊢ ( ( 𝜑 ∧ 𝑧 ∈ 𝑍 ) → 𝑧 ∈ ℤ ) |
| 7 | 2 6 | fprodzcl | ⊢ ( 𝜑 → ∏ 𝑧 ∈ 𝑍 𝑧 ∈ ℤ ) |
| 8 | 7 | adantr | ⊢ ( ( 𝜑 ∧ 𝑚 ∈ 𝑍 ) → ∏ 𝑧 ∈ 𝑍 𝑧 ∈ ℤ ) |
| 9 | dvdsabsb | ⊢ ( ( 𝑚 ∈ ℤ ∧ ∏ 𝑧 ∈ 𝑍 𝑧 ∈ ℤ ) → ( 𝑚 ∥ ∏ 𝑧 ∈ 𝑍 𝑧 ↔ 𝑚 ∥ ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) ) ) | |
| 10 | 5 8 9 | syl2anc | ⊢ ( ( 𝜑 ∧ 𝑚 ∈ 𝑍 ) → ( 𝑚 ∥ ∏ 𝑧 ∈ 𝑍 𝑧 ↔ 𝑚 ∥ ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) ) ) |
| 11 | 10 | biimpd | ⊢ ( ( 𝜑 ∧ 𝑚 ∈ 𝑍 ) → ( 𝑚 ∥ ∏ 𝑧 ∈ 𝑍 𝑧 → 𝑚 ∥ ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) ) ) |
| 12 | 11 | ralimdva | ⊢ ( 𝜑 → ( ∀ 𝑚 ∈ 𝑍 𝑚 ∥ ∏ 𝑧 ∈ 𝑍 𝑧 → ∀ 𝑚 ∈ 𝑍 𝑚 ∥ ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) ) ) |
| 13 | 4 12 | mpd | ⊢ ( 𝜑 → ∀ 𝑚 ∈ 𝑍 𝑚 ∥ ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) ) |
| 14 | 3 | breq2i | ⊢ ( 𝑚 ∥ 𝑃 ↔ 𝑚 ∥ ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) ) |
| 15 | 14 | ralbii | ⊢ ( ∀ 𝑚 ∈ 𝑍 𝑚 ∥ 𝑃 ↔ ∀ 𝑚 ∈ 𝑍 𝑚 ∥ ( abs ‘ ∏ 𝑧 ∈ 𝑍 𝑧 ) ) |
| 16 | 13 15 | sylibr | ⊢ ( 𝜑 → ∀ 𝑚 ∈ 𝑍 𝑚 ∥ 𝑃 ) |