• It is a deceptively simple question that is comprehensible even to a child: What is the largest sofa that can pivot around an L-shaped hallway corner without lifting, squishing or tilting it? Although it still seems easy to solve, the problem has foxed math sleuths for more than 50 years.
• That’s because the challenge for mathematicians is both finding the largest sofa and proving it to be the largest. Without formal proof, it’s always possible someone will come along with a better solution.
• The largest area that will fit around a corner is called the “sofa constant”.
• It is measured in units where one unit corresponds to the width of the hallway.
• The largest sofa that can practically achieve the aims of the challenge is the Gerver sofa, which is shaped a bit like an old telephone handset.

Source:TH