Classic
Ptolemy Relation and Friends
February 11, 2023
AUTHOR: A. Felikson (Updated 4/4/23): In recent decades, identities similar to the one in Ptolemy’s theorem started to pop up in many fields in connection to the notion of cluster algebras introduced and studied since 2000 by Fomin and Zelevinsky. In this brief note we will try to describe several animals from this big and rich zoo.
Freedman’s Hard Decomposition Theorem
November 2, 2022
AUTHOR : R. Kirby :EDITORS : J. Hass and R. Ghrist ART : J. Hass INTRODUCTION In his celebrated paper [8], Mike Freedman showed
An Aperiodic Set of Eleven Wang Tiles
July 24, 2022
AUTHORS : B. Durand and A. Shen : EDITOR/ART : R. Ghrist : This is a review of E. Jeandel and M. Rao, “An