Temporal Data Modeling and Reasoning for Information Systems

Temporal knowledge representation and reasoning is a major research field in Artificial Intelligence, in Database Systems, and in Web and Semantic Web research. The ability to model and process time and calendar data is essential for many applications like appointment scheduling, planning, Web services, temporal and active database systems, adaptive Web applications, and mobile computing applications. This article aims at three complementary goals. First, to provide with a general background in temporal data modeling and reasoning approaches. Second, to serve as an orientation guide for further specific reading. Third, to point to new application fields and research perspectives on temporal knowledge representation and reasoning in the Web and Semantic Web

The Effects of Monetary Policy in the Czech Republic: An Empirical Study

within VAR, structural VAR, and the Factor-Augmented VAR framework. We document a well-functioning transmission mechanism similar to the euro area countries, especially in terms of persistence of monetary policy shocks. Subject to various sensitivity tests, we find that contractionary monetary policy shock has a negative effect on the degree of economic activity and price level, both with a peak response after one year or so. Regarding the prices at the sectoral level, tradables adjust faster than non-tradables, which is in line with microeconomic evidence on price stickiness. There is no price puzzle, as our data come from single monetary policy regime. There is a rationale in using the real-time output gap instead of current GDP growth as using the former results in much more precise estimates. The results indicate a rather persistent appreciation of domestic currency after monetary tightening with a gradual depreciation afterwards.http://deepblue.lib.umich.edu/bitstream/2027.42/64350/1/wp922.pd

The Theory of Stochastic Space-Time. II. Quantum Theory of Relativity

The Nelson stochastic mechanics is derived as a consequence of the basic physical principles such as the principle of relativity of observations and the invariance of the action quantum. The unitary group of quantum mechanics is represented as the transformations of the systems of perturbing devices. It is argued that the physical spacetime has a stochastic nature, and that quantum mechanics in Nelson's formulation correctly describes this stochasticity.Comment: Published in "Zakir Z. (2003) Structure of Space-Time and Matter. CTPA, Tashkent"; Part 1: hep-th/981225

Astrophysical Tests of Kinematical Conformal Cosmology in Fourth-Order Conformal Weyl Gravity

In this work we analyze kinematical conformal cosmology (KCC), an alternative cosmological model based on conformal Weyl gravity (CG), and test it against current type Ia supernova (SNIa) luminosity data and other astrophysical observations. Expanding upon previous work on the subject, we revise the analysis of SNIa data, confirming that KCC can explain the evidence for an accelerating expansion of the Universe without using dark energy or other exotic components. We obtain an independent evaluation of the Hubble constant, H_{0} = 67.53 km/s Mpc, very close to the current best estimates. The main KCC and CG parameters are re-evaluated and their revised values are found to be close to previous estimates. We also show that available data for the Hubble parameter as a function of redshift can be fitted using KCC and that this model does not suffer from any apparent age problem. Overall, KCC remains a viable alternative cosmological model, worthy of further investigation.Comment: 31 pages, including 5 figures and 2 tables. Minor changes and references added. Final version published in Galaxies, Special Issue: Beyond Standard Gravity and Cosmolog

Splitting schedules for Internet broadcast communication

The broadcast disk provides an effective way to transmit information from a server to many clients. Work has been done to schedule the broadcast of information in a way that minimizes the expected waiting time of the clients. Much of this work has treated the information as indivisible blocks. We look at splitting items into smaller pieces that need not be broadcast consecutively. This allows us to have better schedules with lower expected waiting times. We look at the case of two items of the same length, each split into two halves, and show how to achieve optimal performance. We prove the surprising result that there are only two possible types of optimal cyclic schedules for items 1, and 2. These start with 1122 and 122122. For example, with demand probabilities p1= 0.08 and p2= 0.92, the best order to use in broadcasting the halves of items 1 and 2 is a cyclic schedule with cycle 122122222. We also look at items of different lengths and show that much of the analysis remains the same, resulting in a similar set of optimal schedules