  Neural codes, represented as collections of binary strings called codewords,
are used to encode neural activity. A code is called convex if its codewords
are represented as an arrangement of convex open sets in Euclidean space.
Previous work has focused on addressing the question: how can we tell when a
neural code is convex? Giusti and Itskov identified a local obstruction and
proved that convex neural codes have no local obstructions. The converse is
true for codes on up to four neurons, but false in general. Nevertheless, we
prove this converse holds for codes with up to three maximal codewords, and
moreover the minimal embedding dimension of such codes is at most two.
