One of my favorite mathematical anecdotes is the following story that Gian-Carlo Rota told about Solomon Lefschetz: He [Solomon Lefschetz] liked to repeat, as an example of mathematical pedantry, the story of one of E. H. Moore’s visits to Princeton, when Moore started a lecture by saying, “Let a be […]

Estimated reading time: 10 minutes

Here is a fun combinatorial puzzle. I’ve probably seen this used to teach before, but let’s try to define or work this one from memory. I would love to hear more solutions/analyses of this problem. Suppose you have n kettles of soup labeled 0 through n-1. For our problem we […]

Estimated reading time: 14 minutes

While working on a variation of the RcppDynProg algorithm we derived the following beautiful identity of 2 by 2 real matrices: The superscript “top” denoting the transpose operation, the ||.||^2_2 denoting sum of squares norm, and the single |.| denoting determinant. This is derived from one of the check equations […]

Estimated reading time: 33 seconds

I recently wrote a tiny bit about the style of the original published proof of the Erdős-Ko-Rado theorem. In this note I’ll write a bit about the theorem and a bit more about the style of some later proofs. In particular I want to write about two different readings of […]

Estimated reading time: 12 minutes

Here is a neat example of famous mathematician Pál Erdős (often rendered in English as Paul Erdős) writing like a programmer in 1961. He goes to some trouble to introduce notation that allows him to index everything from zero.

Estimated reading time: 1 minute

A recent run of too many articles on the same topic (exhibits: A, B and C) puts me in a position where I feel the need to explain my motivation. Which itself becomes yet another article related to the original topic. The explanation I offer is: this is the way […]

Estimated reading time: 22 minutes