Hana Rudova, Ludek Matyska. Uniform framework for solving over-constrained and
optimization problems. In CP'99 Post-Conference Workshop on Modelling and 
Solving Soft Constraints Alexandria, Virginia, USA, October 1999. 

Abstract:
Variables' annotations as a new uniform framework for solving over-constrained
and optimization problems are introduced. Interpretation of
annotations representing preferences of variables in particular constraints
is presented. Correspondence with constraint hierarchies and possibilistic CSPs
allows solving of over-constrained problems. First steps in optimization area
lead towards computation of variable ordering based on annotations.
Real university timetabling problem is described and solved with annotations.