Hypergraph chromatic index
= Hypergraph chromatic index
{title2=$\chi^{\prime}(H)$}
The chromatic index of a <hypergraph> is the minimum number of colours needed to colour its edges so that intersecting edges have different colours. Each colour class is a <matching in a hypergraph>. It is at least the maximum <hypergraph vertex degree>, and at most $r(\Delta-1)+1$ for an $r$-uniform <hypergraph> of maximum degree $\Delta$, by greedily colouring edges: an edge meets at most $r(\Delta-1)$ others.