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Description: The sequence S of finite products, where every factor is added an "always smaller" amount, converges to the finite product of the factors. (Contributed by Glauco Siliprandi, 8-Apr-2021)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | fprodaddrecnncnv.1 | ⊢ Ⅎ 𝑘 𝜑 | |
| fprodaddrecnncnv.2 | ⊢ ( 𝜑 → 𝑋 ∈ Fin ) | ||
| fprodaddrecnncnv.3 | ⊢ ( ( 𝜑 ∧ 𝑘 ∈ 𝑋 ) → 𝐴 ∈ ℂ ) | ||
| fprodaddrecnncnv.4 | ⊢ 𝑆 = ( 𝑛 ∈ ℕ ↦ ∏ 𝑘 ∈ 𝑋 ( 𝐴 + ( 1 / 𝑛 ) ) ) | ||
| Assertion | fprodaddrecnncnv | ⊢ ( 𝜑 → 𝑆 ⇝ ∏ 𝑘 ∈ 𝑋 𝐴 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | fprodaddrecnncnv.1 | ⊢ Ⅎ 𝑘 𝜑 | |
| 2 | fprodaddrecnncnv.2 | ⊢ ( 𝜑 → 𝑋 ∈ Fin ) | |
| 3 | fprodaddrecnncnv.3 | ⊢ ( ( 𝜑 ∧ 𝑘 ∈ 𝑋 ) → 𝐴 ∈ ℂ ) | |
| 4 | fprodaddrecnncnv.4 | ⊢ 𝑆 = ( 𝑛 ∈ ℕ ↦ ∏ 𝑘 ∈ 𝑋 ( 𝐴 + ( 1 / 𝑛 ) ) ) | |
| 5 | eqid | ⊢ ( 𝑥 ∈ ℂ ↦ ∏ 𝑘 ∈ 𝑋 ( 𝐴 + 𝑥 ) ) = ( 𝑥 ∈ ℂ ↦ ∏ 𝑘 ∈ 𝑋 ( 𝐴 + 𝑥 ) ) | |
| 6 | oveq2 | ⊢ ( 𝑚 = 𝑛 → ( 1 / 𝑚 ) = ( 1 / 𝑛 ) ) | |
| 7 | 6 | cbvmptv | ⊢ ( 𝑚 ∈ ℕ ↦ ( 1 / 𝑚 ) ) = ( 𝑛 ∈ ℕ ↦ ( 1 / 𝑛 ) ) |
| 8 | 1 2 3 4 5 7 | fprodaddrecnncnvlem | ⊢ ( 𝜑 → 𝑆 ⇝ ∏ 𝑘 ∈ 𝑋 𝐴 ) |