Consider the optimal perfect matching problem on a bipartite graph G= (X $$\cup$$ Y, E) with $$\vert X \vert = \vert Y \vert$$ and a weight function $$w: E \to \mathbb{R}$$. We want to find a perfect matching with maximal sum of edge weights. Where all edges in E are between X and Y only. Is there a canonical example of a bipartite graph that does NOT have a perfect matching? (so called inadmissible bipartite graphs).