April has been a very busy month for me for various reasons. One of them is that I had three preprints put on the arXiv: Let me discuss all of these here with a focus on the first of the three. In each case I try to focus on aspects which are not the focus […]
Addendum (09 April 2025): Several people have told us about a minor mistake in our application of the LLLL. We have an internal version which corrects this. At some point we will correct our preprint on the arXiv. With 7 authors decision making takes some time. Intersecting families and, in particular, the Erdős-Ko-Rado theorem were […]
Earlier this year there was a conference in Budapest, Hungary, named Sum(m)it280, to honor the cumulative 280th birthday of the Péter Frankl, Zoltán Füredi, Ervin Győri and János Pach. There the organizers asked participants for survey articles for a conference volume on extremal problems in combinatorics and geometry. Now I have worked a reasonably amount […]
One of the greatest discovery of in the theory of distance-regular graphs has been the twisted Grassmann graph by Edwin van Dam and Jack Koolen. Here I want to describe a small variation of their construction for the twisted $ {D_{5,5}(q)}$ graph. This post mostly to preserve my blackboard on the topic. (I tend to […]
I have uploaded a preprint which concludes a joint work with John Bamberg and Ferdinand Ihringer that started last year during their visit to TU Delft. In this work, we have done one of my favorite things in mathematics research: combining unrelated topics to create something new in each of them. Here is a quick […]
This week I put two new preprint on the arXiv. Both are on a similar theme, so I will discuss them together. One is with Morgan Rodgers on regular sets of lines in rank 3 polar spaces. The other one is solves a problem which I have been thinking about very regularly since November 2017: […]
Apparently, I described a very elegant argument to give a lower bound on the second largest eigenvalue of the adjacency matrix of a regular graph last year. This was pointed out in two recent preprints by Eero Räty, Benny Sudakov, and Istvan Tomon. This blog post is to describe the very short argument and how […]
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). […]
