ESSENCE is a high-level constraint specification language; it allows a combinatorial (optimisation) problem to be specified at a level of abstraction above that at which modelling decisions are made. Version 1.1.0 of the language is now fully defined.

The most notable feature of ESSENCE is the support for high-level nested types, for example a ‘set (size 3) of partitions of int(1..20)’.

There has been one publicly available implementation of ESSENCE:

All the Essence models can be downloaded as a zip file