I wrote something about this some years ago, and in particular, connected it to the question&#x2F;problem of clashes when generating (hopefully) UIDs.<p><a href="http:&#x2F;&#x2F;www.solipsys.co.uk&#x2F;new&#x2F;TheBirthdayParadox.html?HN_20151220" rel="nofollow">http:&#x2F;&#x2F;www.solipsys.co.uk&#x2F;new&#x2F;TheBirthdayParadox.html?HN_201...</a><p>This submitted wikipedia link is more complete, but I hope mine is more readable as an introduction to the question.