  This paper overviews work on the use of simple chemical reactions to
calculate Voronoi diagrams and undertake other related geometric calculations.
This work highlights that this type of specialised chemical processor is a
model example of a parallel processor. For example increasing the complexity of
the input data within a given area does not increase the computation time.
These processors are also able to calculate two or more Voronoi diagrams in
parallel. Due to the specific chemical reactions involved and the relative
strength of reaction with the substrate (and cross-reactivity with the
products) these processors are also capable of calculating Voronoi diagrams
sequentially from distinct chemical inputs. The chemical processors are capable
of calculating a range of generalised Voronoi diagrams (either from circular
drops of chemical or other geometric shapes made from adsorbent substrates
soaked in reagent), skeletonisation of planar shapes and weighted Voronoi
diagrams (e.g. additively weighted Voronoi diagrams, Multiplicitavely weighted
Crystal growth Voronoi diagrams). The paper will also discuss some limitations
of these processors. These chemical processors constitute a class of pattern
forming reactions which have parallels with those observed in natural systems.
It is possible that specialised chemical processors of this general type could
be useful for synthesising functional structured materials.
