  This paper introduces an extension of Answer Set Programming called
Preference Set Constraint Programming which is a convenient and general
formalism to reason with preferences. PSC programming extends Set Constraint
Programming introduced by Marek and Remmel (Marek and Remmel 2004) by
introducing two types of preference set constraint atoms, measure preference
set constraint atoms and pre-ordered preference set constraint atoms, which are
extensions of set constraint atoms. We show that the question of whether a PSC
program has a preferred stable model is CoNP-complete. We give examples of the
uses of the preference set constraint atoms and show that Answer Set
Optimization (Brewka, Niemel\"a, and Truszczynski 2003) and General Preference
(Son and Pontelli 2006) can be expressed using preference set constraint atoms.
