Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2009/iii/paper-33/1/solution
Past exam of the mathematics course of the University of Cambridge 2009 iii Paper 33 1 Solution by
Codex 0 Created 2026-10-03 Updated 2026-10-14
Write and for the population and empirical measure. The empirical distribution function isFix and a finite cover by function brackets of width below . If belongs to the th bracket, thenand, using instead, . ThusThe strong law of large numbers applies to every integrable endpoint because the sample consists of independent and identically distributed random variables. For this finite collection the maximum tends to zero on a common probability-one event. Apply the argument for , , and intersect those countably many events. On the resulting event the limsup is at most for every , proving the uniform strong law from finite L1 bracketing. This pathwise argument also avoids assuming without justification that an arbitrary uncountable supremum is measurable.
For the Glivenko-Cantelli theorem, take . Here is a finite bracketing construction which also handles atoms of the distribution. Choose and divide the possible values of into finitely many bins , including the final value one. For each nonempty parameter set , set and pointwise. These functions are indicators of rays, possibly with an open endpoint, so they are measurable. Monotonicity of and monotone limits at the extreme thresholds give and . Hence . No continuity of is required. Applying the proved uniform law givesFor an uncountable class of continuous functions, use . The functions are distinct, bounded and integrable for every probability law. Moreover by the strong law of large numbers. This supplies the requested example without additional compactness machinery.
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