Say you’re at a party with nine other people and everyone shakes everyone else’s hand exactly once. How many handshakes take place? This is the “handshake problem,” and it’s one of my favorites. As a ...

To minimize brain strain when thinking recursively, start simply, look for a pattern and let the pattern do the work. Our April Insights puzzle explored the magical concept of recursion, a ...

Topological recursion is a new universal structure, which has been recently applied to different applications like the Kontsevich model and Mirzakhani's recursions codifying intersection numbers and ...