Sj. Brams et al., A MOVING-KNIFE SOLUTION TO THE 4-PERSON ENVY-FREE CAKE-DIVISION PROBLEM, Proceedings of the American Mathematical Society, 125(2), 1997, pp. 547-554
We present a moving-knife procedure, requiring only 11 cuts, that prod
uces an envy-free allocation of a cake among four players and discuss
possible extensions to five players.