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2024-10-28 / Last updated : 2024-10-28 Ferdinand Ihringer Mathematics

The Twisted $D_{5,5}(q)$ Graph

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 […]

2023-12-08 / Last updated : 2023-12-08 Ferdinand Ihringer Mathematics

Classifying Cameron-Liebler Sets/Boolean Degree 1 Functions

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: […]

2022-08-24 / Last updated : 2024-09-26 Ferdinand Ihringer Miscellaneous

Bielefeld Buildings Conspiracy

The 28th edition of the Buildings conference is held in Ghent (where I am currently based) this September. [Note that this is unrelated to the actually buildings which you live and work in. The mathematical branch of building theory is abstract algebra. I have one post mentioning them.] Now I am not in the habit […]

2017-11-05 / Last updated : 2024-10-25 Ferdinand Ihringer Mathematics

Erdős-Ko-Rado Theorems for Spherical Buildings

Today’s topic combines three of my favorite subjects: Erdős-Ko-Rado theorems (EKR theorems), finite buildings and spectral techniques. All of these topics deserve their own books (and have them, here some examples which I read: Erdos-Ko-Rado Theorems: Algebraic Approaches by Chris Godsil and Karen Meagher, Spectra of Graphs by Andries E. Brouwer and Willem H. Haemers, The Structure of Spherical […]

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