A common motivation for developing computational frameworks for diagrammati
c reasoning is the hope that they might serve as re-configurable tools for
studying human problem solving performance. Despite the ongoing debate as t
o the precise mechanisms by which diagrams, or any other external represent
ation, are used in human problem solving, there is little doubt that diagra
mmatic representations considerably help humans solve certain classes of pr
oblems. In fact, there are a host of applications of diagrams and diagramma
tic representations in computing, from data presentation to visual programm
ing languages. In contrast to both the use of diagrams in human problem sol
ving and the ubiquitous use of diagrams in the computing industry, the topi
c of this review is the use of diagrammatic representations in automated pr
oblem solving. We therefore investigate the common, and often implicit, ass
umption that if diagrams are so useful for human problem solving and are so
apparent in human endeavour, then there must be analogous computational de
vices of similar utility.