Abstrakt
The central levels problemasserts that the subgraph of the (2m + 1)-dimensional hypercube induced by all bitstrings with at least m + 1 - l many 1s and at most m + l many 1s, i.e., the vertices in the middle 2 l levels, has a Hamilton cycle for any m >= 1and 1 = 1and 1 = 2, that contains the symmetric chain decomposition constructed by Greene and Kleitman in