  Split preorders are preordering relations on a domain whose composition is
defined in a particular way by splitting the domain into two disjoint subsets.
These relations and the associated composition arise in categorial proof theory
in connection with coherence theorems. Here split preorders are represented
isomorphically in the category whose arrows are binary relations, where
composition is defined in the usual way. This representation is related to a
classical result of representation theory due to Richard Brauer.
