We characterize noncommutative Frobenius algebras A in terms of the existence of a coproduct which is a map of left A-modules. We show that the category of right (left) comodules over A, relative to this coproduct, is isomorphic to the category of right (left) modules. This isomorphism enables a reformulation of the cotensor product of Eilenberg and Moore as a functor of modules rather than com...

We introduce an approach to view materialization which is based on relational reformulation. In this context, we present a method for automatically discovering views of the stored relations that are not already deened yet present valuable opportunities for materialization. The proposed reformu-lation algorithm works oo-line and consists of two stages. At the rst stage, Datalog rules relevant to...

Let (MQP ) be a general mixed integer quadratic program that consists of minimizing a quadratic function subject to linear constraints. In this paper, we present a convex reformulation of (MQP ), i.e. we reformulate (MQP ) into an equivalent program, with a convex objective function. Such a reformulation can be solved by a standard solver that uses a branch and bound algorithm. We prove that ou...

Query reformulation is a key user behavior during Web search. Our research goal is to develop predictivemodels of query reformulation duringWeb searching.This article reports results from a study in which we automatically classified the query-reformulation patterns for 964,780 Web searching sessions, composed of 1,523,072 queries, to predict the next query reformulation. We employed an n-gram m...