[30] [Nested interval theorem／区間縮小法(2)] ∀n∈N. [a_n, b_n] ⊃ [a_n+1, b_n+1] ∧ b_n - a_n → 0 (as n → ∞) ⇒ ∃c∈R. ∩_n∈N [a_n, b_n] = {c} ∧ a_n, b_n → c (as n → ∞)

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