Paper 3, Section II, E

Analysis II | Part IB, 2012

Let fnf_{n} be a sequence of continuous functions on the interval [0,1][0,1] such that fn(x)→f(x)f_{n}(x) \rightarrow f(x) for each xx. For the three statements:

(a) fn→ff_{n} \rightarrow f uniformly on [0,1][0,1];

(b) ff is a continuous function;

(c) ∫01fn(x)dx→∫01f(x)dx\int_{0}^{1} f_{n}(x) d x \rightarrow \int_{0}^{1} f(x) d x as n→∞;n \rightarrow \infty ;

say which of the six possible implications (a)⇒(b),(a)⇒(c),(b)⇒(a),(b)⇒(c)(a) \Rightarrow(b),(a) \Rightarrow(c),(b) \Rightarrow(a),(b) \Rightarrow(c), (c)⇒(a),(c)⇒(b)(c) \Rightarrow(a),(c) \Rightarrow(b) are true and which false, giving in each case a proof or counterexample.

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