Partiality and Approximation Schemes for Local Consistency in Networks of Constraints [Technical Report] CTI TR 95.5.23 - Δενδρής, Νίκος; Θηλυκός, Δημήτρης; Κυρούσης, Λευτέρης Μ.; Σταματίου, Ι. (Computer Technology Institute, 1995)