The ambidextrous moving sofa constant C41b asks for the maximum area of a sofa, as defined in C41a that can navigate both left and right corners inside a Z-shaped corridor of width 1, where the corners are sufficiently far apart.
That is, the shape of the largest area (the "sofa") that can be moved from one end of the corridor to the other by a continuous rigid motion (translation and rotation).
Trivially, C41a≥C41b