Tag Archives: Hadamard matrix

A public lecture

This evening, Jonathan Jedwab gave a public lecture, in celebration of the fact that it is Jacques Hadamard‘s 150th birthday. The title of the lecture was “What is a research mathematician?”, and the hook linking the two was Hadamard matrices. … Continue reading

Posted in events | Tagged , , , , | Leave a comment

A matrix problem

Suppose you are given n linearly independent vectors in n-dimensional Euclidean space. You move the vectors so that each vector becomes longer, but their inner products remain the same. What happens to the volume of the parallelepiped they span? This … Continue reading

Posted in open problems | Tagged , , , , , , , | 7 Comments

Team games, 1

Laurent asked on my blog: Given n players, arrange a competition in which, in each match, two teams of k players play each other. We require that any two players are on the same team in a fixed number s … Continue reading

Posted in exposition | Tagged , | 6 Comments