Hierarchical Models for Relational Event Sequences

Interaction within small groups can often be represented as a sequence of events, where each event involves a sender and a recipient. Recent methods for modeling network data in continuous time model the rate at which individuals interact conditioned on the previous history of events as well as actor covariates. We present a hierarchical extension for modeling multiple such sequences, facilitating inferences about event-level dynamics and their variation across sequences. The hierarchical approach allows one to share information across sequences in a principled manner---we illustrate the efficacy of such sharing through a set of prediction experiments. After discussing methods for adequacy checking and model selection for this class of models, the method is illustrated with an analysis of high school classroom dynamics

Testing the spatial scale and the dynamic structure in regional models (a contribution to spatial econometric specification analysis)

This article addresses the problem of specification uncertainty in modeling spatial economic theories in stochastic form. It is ascertained that the traditional approach to spatial econometric modeling does not adequately deal with the type and extent of specification uncertainty commonly encountered in spatial economic analyses. Two alternative spatial econometric modeling procedures proposed in the literature are reviewed and shown to be suitable for analyzing systematically two sources of specification uncertainty, viz., the level of aggregation and the spatio-temporal dynamic structure in multiregional econometric models. The usefulness of one of these specification procedures is illustrated by the construction of a simple multiregional model for The Netherlands

Sound and Automated Synthesis of Digital Stabilizing Controllers for Continuous Plants

Modern control is implemented with digital microcontrollers, embedded within a dynamical plant that represents physical components. We present a new algorithm based on counter-example guided inductive synthesis that automates the design of digital controllers that are correct by construction. The synthesis result is sound with respect to the complete range of approximations, including time discretization, quantization effects, and finite-precision arithmetic and its rounding errors. We have implemented our new algorithm in a tool called DSSynth, and are able to automatically generate stable controllers for a set of intricate plant models taken from the literature within minutes.Comment: 10 page

Market Reforms and Growth in Post-socialist Economies: Evidence from Panel Cointegration and Equilibrium Correction Model

In this paper the impact of market reforms on economic growth has been analyzed using the panel data for 26 post-socialist economies over the period between 1989 and 2005. Taking into account the dynamic properties of the data, the concepts of cointegration and equilibrium correction model for panel data has been used as the analytical framework. First, well-specified regression models have been obtained. Second, long and short run aspects of ëreforms-growthí relationship have been considered. Out analysis has detected the existence of cointegration between the level of ERBD reform index and the level of real GDP per capita. This is interpreted as the presence of the long run relationship between these indicators. Third, it has been found that there is a statistically significant positive influence of economic reforms on economic growth in the long run. In addition, market reforms positively influence economic growth in the short-run, but with a one-year lag. The equilibrium correction mechanism in corresponding regressions reflects existing biases of the analyzed indicators from the equilibrium trajectory, as well as direction and speed of adjustment to this trajectory. Our approach to modeling of the relationship between market reforms and economic growth explains a puzzle of high rates of economic growth in some countries with a relatively low level of ERBD reform index. Finally, in contrast to other studies employing a different methodology, statistically significant influence of economic growth on market reforms has been established both in the long and short run, our study shows that there is no such relationship.http://deepblue.lib.umich.edu/bitstream/2027.42/64403/1/wp936.pd

A Rewriting-Logic-Based Technique for Modeling Thermal Systems

This paper presents a rewriting-logic-based modeling and analysis technique for physical systems, with focus on thermal systems. The contributions of this paper can be summarized as follows: (i) providing a framework for modeling and executing physical systems, where both the physical components and their physical interactions are treated as first-class citizens; (ii) showing how heat transfer problems in thermal systems can be modeled in Real-Time Maude; (iii) giving the implementation in Real-Time Maude of a basic numerical technique for executing continuous behaviors in object-oriented hybrid systems; and (iv) illustrating these techniques with a set of incremental case studies using realistic physical parameters, with examples of simulation and model checking analyses.Comment: In Proceedings RTRTS 2010, arXiv:1009.398