Barcode restoration and division modulo a prime
Yesterday, I came across a puzzle in which we had to decode a barcode (Code 128) of which a piece had been obfuscated. The math involved in this is very elegant, so I decided to write it down, hoping that one day someone will benefit from it.
Repeated substitution and Chebyshev polynomials
Recently, I was experimenting with a process in which we start with the polynomial and obtain by substituting , for some number . By accident, I saw that both for and , . Of course, for , as well. This made me wonder: for which values of do we have for some ?
Group theory 101.0
This is an introduction to group theory, covering the concepts of groups, subgroups and (homo)morphisms.
I am setting up this blog to share interesting stuff I find on the internet, in my books or in my lectures.