Tomaž Pisanski: On the Hamilton decomposition of joins of graphs

Povzetek. It has been over 30 years since I first submitted a paper on Hamilton surface decomposition of graphs for possible publication. The paper has been written jointly with Brian Alspach and relied on a key, yet unproven lemma about Hamilton decomposition of certain joins of graphs. Recently Brian made a breakthrough by proving the lemma. I am giving this talk in order to understand better his proof that involves orthogonal matchings