Introduced the notion of a <i>simplicial complex</i> K. Introduced convex hulls in order to explain what is meant by the <i>geometric realisation</i> |K| of a simplicial complex K. Ended up explaining how, from an nxn distance matrix, we can construct a simplicial complex K<sub>&#949;</sub> for any choice of threshold &#949;>0. In this way we can associate a topological space |K<sub>&#949;</sub>| to any distance matrix.