As the number of applications that rely on XML data increases, so does the need for performing efficient XML query evaluation. A critical part of the solution involves providing new techniques for designing XML indexes and lookup algorithms. In this paper, we leverage the results of our research on coupling the partitions induced by fragments of XPath algebra and those induced by the structural...

We introduce a generalized cake-cutting problem in which we seek to divide multiple cakes so that two players may get their most-preferred piece selections: a choice of one piece from each cake, allowing for the possibility of linked preferences over the cakes. For two players, we show that disjoint envy-free piece selections may not exist for two cakes cut into two pieces each, and they may no...

Our approach to the automatic acquisition of disjointness axioms relies on a machine learning classifier that determines disjointness of any two classes. The classifier is trained based on a “Gold Standard” of manually created disjointness axioms, i.e. pairs of classes each of which is associated with a label – “disjoint” or “not disjoint” – and a vector of feature values. As in our earlier exp...

In the eld of visual control of robot motion, visual servoing has been proposed as the suitable control strategy to cope with imprecise models and calibration errors. Remaining problems such as the necessity of a high rate of visual feedback are deemed to be solvable by the development of real-time vision modules. However, human grasping, which still outshines its robotic counterparts especiall...

We describe the modular development of correct parallel software with the Meander system from high-level speciications down to a concrete implementation, based on a communicating algebra formalism. We focus on the external behavior of the components and keep the behavioral properties through reenement and abstraction. A combination of a exible set of syntactical metarules and nite model checkin...

We prove existence of envy-free allocations in markets with heterogenous indivisible goods and money, when a given quantity is supplied from each of the goods and agents have unit demands. We depart from most of the previous literature by allowing agents’ preferences over the goods to depend on the entire vector of prices. Our proof uses Shapley’s K-K-M-S theorem and Hall’s marriage lemma. We t...

We discuss the existential fragments of two theories of concatenation. These theories describe concatenation of possibly nested lists in the algebra of nite trees with lists and in the algebra of rational trees with lists. Syntax and the choice of models are motivated by the treatment of lists in PROLOG III. In a recent prototype of this language, Colmerauer has integrated a built-in concatenat...

We study the classic problem of fairly dividing a heterogeneous resource (”cake”) among several agents with different preferences. In our setting, the resource is already divided among several ”old” agents. When ”young” agents come, the resource should be re-divided in a way that is fair both for the young and for the old agents. Motivated by land redivision and other two-dimensional division p...

The contraction model of Field and Colgate for proto-galaxies, first proposed to describe the observed properties of quasars, is generalized and used to investigate the evolution of galaxies. The LEDA data base for elliptical, spiral, compact and diffuse galaxies is employed and it is shown that the above model is consistent with observational evidences regarding their dynamical evolution, star...