Antifactors of regular bipartite graphs
Let $G=(X,Y;E)$ be a bipartite graph, where $X$ and $Y$ are color classes Acrylic First Day Of School Sign and $E$ is the set of edges of $G$.Lov'asz and Plummer cite{LoPl86} asked whether one can decide in polynomial time that a given bipartite graph $G=(X,Y; E)$ admits a 1-anti-factor, that is subset $F$ of $E$ such that $d_F(v)=1$ for all $vin X