Geoffrey Exoo and Dan Ismailescu, or 2 Men for 2 Forbidden Distances

We have a team of a Geombinatorics Editor Geoffrey Exoo and Dan Ismailescu. You may recall Chap. 16 of this book dedicated to their construction of unit-distance graphs of successive orders 21, 19, and 17 of girth 4 and proving that 17 is best possible, thus settling my open problem 15.4 posed in the first edition of this book [Soi44]. You also saw Geoffrey’s lower bounds for Ramsey Numbers, the Schur number 5, and many more results.