Object Identity as Search Bias for Pattern Spaces

In the context of frequent pattern discovery, we present a generality relation, called thetaOI-subsumption, which is based on the assumption of Object Identity in spaces of patterns to be intended as existentially quantified conjunctive formulae. The resulting generality order ¹OI seems appropriate for organizing efficiently the space of DATALOG patterns over structured domains. Indeed we prove the existence of ideal refinement operators for ¹OI-ordered spaces and the monotonicity of ¹OI with respect to pattern support. Features of such spaces are illustrated by means of an example of frequent pattern discovery in spatial data.