Chen, W.Y.C. and R.P. Stanley, Derangements on the n-cube, Discrete Mathematics 115 (1993) 65-15. Let Q. be the n-dimensional cube represented by a graph whose vertices are sequences of O’s and l’s of length n, where two vertices are adjacent if and only if they differ only at one position. A k-dimensional subcube or a k-face of Q. is a subgraph of Q. spanned by all the vertices u1 u2 u, with c...