Twenty-five years too late to help Ross get his new couch into his apartment in "Friends," a mathematician has finally solved the pesky "sofa problem." The math problem delineates the largest-size ...

In a scene from the classic sitcom, "Friends," the characters Ross, Rachel and Chandler struggle to heft a new couch up the stairs of their apartment building. As they try to get the sofa around the ...

A new proof reveals the answer to the decades-old “moving sofa” problem. It highlights how even the simplest optimization problems can have counterintuitive answers. If you’ve ever moved into a new ...