On the Existence of \((v,4, 1)\)-PMD

FE. Bennett has proved that a \((v, 4, 1)\)-RPMD exists for every positive integer \(v \equiv 1 \pmod{4}\) with the possible exception of \(v = 33, 57, 93\) and \(133\). In this paper, we shall first introduce the concept of an incomplete PMD and use it to establish some construction methods for Mendelsohn designs; then we shall give the following results: (1) a \((v, 4, 1)\)-PMD exists for every positive integer \(v \equiv 0 \pmod{4}\) with the exception of \(v = 4\) and the possible exception of \(v = 8, 12\);(2) a \((v, 4, 1)\)-PMD exists if \(v = 57, 93\) or \(133\).