There are 12 red balls, 15 white balls and 17 black balls in a box. A person extracts all the balls, one at a time. What’s the probability that all the red balls will be extracted before the white balls and that all the white balls will be extracted before the black balls? There are […]
Category: Computational Combinatorics
Quarantine And Bijections
Now the majority of Italy is in lockdown again. So, why not spend some time doing combinatorics. Today’s subject is bashing sums without having to do any calculation. Let’s say we have this sum: One way to do it would be differentiating , then multiplying the result by x and differentiating again. Then we get […]
Using Symmetry
I put this problem in an old team competition I organized. It is not simple, and I asked only for the case where n is even, now I’ll show you the complete version. Let be reals in an interval of lenght 1. Find the maximum value of Now, let’s treat as constants and let be […]