In this paper we provide a characterization of second order fully nonlinear CR invariant equations on the Heisenberg group, which is the analogue in the CR setting of the result proved in the Euclidean setting by A. Li and the first author in [21]. We also prove a comparison principle for solutions of second order fully nonlinear CR invariant equations defined on bounded domains of the Heisenbe...

The applicability of lexicographic comparison in nonmonotonic reasoning with speciicity is investigated. A priority mechanism based on lexicographic comparison is deened for Reiter's default logic. The following principle earlier used by Geener and Pearl in conditional entail-ment is used as the basis for speciicity-based priorities for normal default theories: for each rule there is a context ...

This paper analyzes the stability of a class of discrete linear multidimensional (MD) systems, whose solutions are path dependent and may not be uniquely specified by initial conditions. Based on the concept of solvable Lie algebra and a new comparison principle, it presents a simple necessary and sufficient condition for exponential stability of the MD systems in terms of the spectral radius o...

The oracle model of computation is believed to allow a rigorous proof of quantum over classical computational superiority. Since quantum and classical oracles are essentially different, a correspondence principle is commonly implicitly used as a platform for comparison of oracle complexity. Here, we question the grounds on which this correspondence is based. Obviously, results on quantum speed-...

A collaborative learning environment based on 3D media with interchangeable real and virtual components is introduced. This environment is supported by a special knowledge space, which allows the accumulation of concrete haptic as well as abstract physical and logical knowledge. Firstly we present the concept of complex objects, having a real part and various virtual parts of different levels o...

Process-aware information systems typically involve various kinds of process stakeholders. That, in turn, leads to multiple process models that capture a common process from different perspectives and at different levels of abstraction. In order to guarantee a certain degree of uniformity, the consistency of such related process models is evaluated using formal criteria. However, it is unclear ...

In an assemble-to-order system, a wide variety of products are rapidly assembled from component inventories in response to customer orders. We assume that orders must be filled within a product-specific target lead time. In the event that some of the components required to fill an order are out of stock, these components must be expedited. The objective is to minimize the expected infinite-hori...

We document the central role of repo collateral in tri-party repo pricing. Markets are competitive for repos with safe collaterals, but are severely segmented for repos with risky collaterals such as equities and low-grade corporate bonds. Fund families are the sole contributors of the segmentation, and collateral concentration is the main determinant in the substantial variation in repo pricin...