The *double encoding* [Stergiou WalshStergiou Walsh1999] combines the hidden variable
and the dual encoding. As in the HVE, the set of variables in the
double encoding consists of all the variables of the original
non-binary CSP plus the dual variables. For every dual variable
, there is a binary constraint between and each of the
original variables involved in the corresponding
non-binary constraint . As in the DE, there are also binary
constraints between two dual variables and if the
non-binary constraints and share one or more original
variables.

Nikolaos Samaras 2005-11-09