\documentclass[12pt]{article} \usepackage{amsmath,mathrsfs,bbm} \usepackage{amssymb} \textwidth=4.825in \overfullrule=0pt \thispagestyle{empty} \begin{document} \noindent % % {\bf R. Julian R. Abel, Diana Combe, Adrian M. Nelson and William D. Palmer} % % \medskip \noindent % % {\bf GBRDs with Block Size Three over 2-Groups, Semi-Dihedral Groups and Nilpotent Groups} % % \vskip 5mm \noindent % % % % There are well known necessary conditions for the existence of a generalized Bhaskar Rao design over a group $\mathbb{G}$, with block size $k=3$. We prove that they are sufficient for nilpotent groups $\mathbb{G}$ of even order, and in particular for $2$-groups. In addition, we prove that they are sufficient for semi-dihedral groups. \end{document} .