On the volume of sections of the cube

We study the properties of the maximal volume $k$-dimensional sections of the $n$-dimensional cube $[-1,1{]}^n$. We obtain a first order necessary condition for a $k$-dimensional subspace to be a local maximizer of the volume of such sections, which we formulate in a geometric way. We estimate the length of the projection of a vector of the standard basis of ${\mathbb{R}}^n$ onto a $k$-dimensional subspace that maximizes the volume of the intersection. We find the optimal upper bound on the volume of a planar section of the cube $[-1,1{]}^n,$ $n\ge 2.$