Skip to content
nonconvexcard

Volume concentrates near the boundary

NumericalBeginner⏱ 15 minHigh-Dim Probabilityvolumeballshellhigh dimension

Problem

  1. What fraction of the volume of the unit ball in Rd\R^d lies at radius less than 1−ε1-\eps?
  2. Find the ε\eps for which that fraction is 1%1\%, as a function of dd, and evaluate it for d=3,100,1000d = 3, 100, 1000.
  3. What fraction of the volume of the unit cube [−1,1]d[-1,1]^d lies inside the inscribed ball? Evaluate for d=2,10,100d = 2,10,100 and comment.

Compute the requested quantities and say what they mean. A number without an interpretation is not an answer.

Hints

Hints — 0 of 2 revealed

Solution

Opening this before you have a real attempt on paper is the fastest way to feel like you understand something you cannot reproduce.

Related problems

All problems
SolvedProblemFieldTypeDifficultyTime
Simulate the measure of a spherical cap runHigh-Dim ProbabilityCodingIntermediate30 min
The volumetric lower bound on covering numbersHigh-Dim ProbabilityProofIntermediate30 min
Concentration of the norm — the transfer stepHigh-Dim ProbabilityProofAdvanced30 min
Distance contrast in high dimensionHigh-Dim ProbabilityProofAdvanced1 hour
How many nearly-orthogonal directions fit in R^d?High-Dim ProbabilityProofAdvanced30 min