“The moving sofa problem or sofa problem is a two-dimensional idealisation of real-life furniture-moving problems and asks for the rigid two-dimensional shape o

“The moving sofa problem or sofa problem is a two-dimensional idealisation of real-life furniture-moving problems and asks for the rigid two-dimensional shape of largest area A that can be maneuvered through an L-shaped planar region with legs of unit width.[1] The area A thus obtained is referred to as the sofa constant. The exact value of the sofa constant is an open problem.” — https://en.wikipedia.org/wiki/Moving_sofa_problem https://en.wikipedia.org/wiki/Moving_sofa_problem Familiar to some of us from Douglas Adams' _Dirk Gently's Holistic Detective Agency_.