## Organisers:

## Time:

## Venue:

Hansel's lemma (not Hensel's lemma) states that if the complete graph on $n$ vertices can be expressed as the union of $r$ bipartite graphs $B_1,B_2,\ldots,B_r$ such that $n_i$ is the number of non-isolated vertices in $B_i$, then $n_1+n_2+\cdots+