Poll: Grants & Attributions in Mathematics
Yesterday I received the feedback by referees on one of my grant proposals. Two of the three referee reports were very positive, but, sadly, one was just positive. Hence, I did not receive the highest grade in the evaluation system of the grant agency, only the second highest (that particular grant agency has 7 grades). […]
Finite Geometry Beats the Random Process
I am very happy about today’s result by Sam Mattheus and Jacques Verstraete proving an almost tight bound on the off-diagonal Ramsey number r(4, t). This beats the bound by Bohman and Keevash using the random process. See Anurag’s post above for details. Just yesterday I gave a plenary talk at CanaDAM about off-diagonal Ramsey […]
Mathematicians & Bureaucrats
All (most) math departments have a day where school students come to the department and you do math-y activities with them. In Ghent this day is called UniMath and happened today. My colleague Zhirayr Avetisyan and I contributed a riddle to it. Maybe it was a bit too hard, but I like what we ended […]
Collecting Strongly Regular Graphs
Today I write about a recent hobby of mine: Collecting strongly regular graphs. It started three years ago. You can find my collection on my homepage. I collect many SRGs with known parameters. It started here. This is about size, not quantity, and tries to give an idea how a typical SRG with certain parameters […]
A Boolean Function with Small Degree and Many Variables
Recently, while working on a research project, I got on a tangent. From this tangent, I got on another tangent and that is what I want to write about today: a very nice Boolean function. This example got rediscovered several times for different reasons and, as I try to emphasize from time, I believe that […]
Don’t be a Square (but count them)
One of the structures investigated in finite geometry are related to quadratic forms over finite fields (see below for definitions). Knowledge on the geometry of singular points of quadratic forms is very common and covered in many textbooks on finite geometry, but one cannot say the same for the geometry on non-singular points. This short […]
Almost a Hadamard Matrix
Recently, Yu Hin Au, Nathan Lindzey, and Levent Tunçel published a preprint with various spectral bounds on the arXiv. They investigate generalizations of bounds due to Delsarte and Hoffman in the context of the Lovász-Schrijver SDP. Page 12 of that article I knew for a few more days because Nathan asked me if their bound […]
R(5, 22) and R(6, 21)
A quick post about small Ramsey numbers. I like to write on my blog about things which I do not intend to publish, but also do not want to keep as private knowledge. This is one of these posts. Stanisław P. Radziszowski writes the following in the 15th revision of his survey on small Ramsey […]
A Very Short History of Pseudorandom Cliquefree Graphs
I started writing this blog post some months ago. Occasion was that my paper “A construction for clique-free pseudorandom graphs” (in joint work Anurag Bishnoi and Valentina Pepe) was accepted by Combinatorica with minor revisions. More precisely, one of the referees was unfavorable of publication because he got the impressions that we are simply restating […]