An Instantiation-Based Approach for Solving Quantified Linear Arithmetic

This paper presents a framework to derive instantiation-based decision procedures for satisfiability of quantified formulas in first-order theories, including its correctness, implementation, and evaluation. Using this framework we derive decision procedures for linear real arithmetic (LRA) and linear integer arithmetic (LIA) formulas with one quantifier alternation. Our procedure can be integrated into the solving architecture used by typical SMT solvers. Experimental results on standardized benchmarks from model checking, static analysis, and synthesis show that our implementation of the procedure in the SMT solver CVC4 outperforms existing tools for quantified linear arithmetic

Analyzing financial sectors in transition : with special reference to the Former Soviet Union

This paper proposes a framework for analyzing the evolution of financial sectors in economies transiting from command to market structures. Most commentators have tended to regard this"Transition"as an undifferentiated period to be traversed as rapidly as possible. In doing so they ignore the increasing evidence that the Transition can be an extended, even enduring, state of the world, resulting from a complex interaction of economic, political, cultural and psychological factors. As such, it can and does generate incentives which fundamentally distort the behavior of economic agents in unpredictable ways. The authors argue that one result of ignoring the true messiness of the Transition is that the analysis and policy recommendations offered to governments can be flawed and often provide conclusions which are odds with the reality on the ground. The paper discusses this concern and proposes a simple analytical framework both for focusing on the Transition itself and also for use in defining and evaluating possible public policy interventions for the banking sector. This paper is organized as follows. Section II sketches the main shortcomings of the traditional analyses of the financial sector in transition - particularly the limitations of current thinking on the sequencing of financial sector reforms. Section III introduces and elaborates on the basic framework proposed. Section IV uses the framework to distill some simple but important propositions about transition banking. Section V provides an initial qualitative test of the framework, by using it as a lens through which to view some of the characteristics of transition banks which we have observed. It shows that behavior patterns which, at first glance, seem curious and counterproductive, do indeed have a rational explanation when viewed in relation to the analytical framework we propose. Section VI applies the proposed analytical approach to assess the appropriateness of various interventions -- especially those which have proved popular in the World Bank -- to support the financial sector transition. Two Annexes then elaborate particular aspects of the analysis. Annex 1 assesses how our analysis might recondition thinking about the appropriate regulatory and supervisory structures for transition banking. Annex 2 provides some initial empirical results based on our proposed framework of analysis.Environmental Economics&Policies,Banks&Banking Reform,Financial Intermediation,Payment Systems&Infrastructure,Labor Policies,Financial Intermediation,Environmental Economics&Policies,Insurance&Risk Mitigation,Financial Crisis Management&Restructuring,Banks&Banking Reform

High-Speed, Photon Counting CCD Cameras for Astronomy

The design of electron multiplying CCD cameras require a very different approach from that appropriate for slow scan CCD operation. This paper describes the main problems in using electron multiplying CCDs for high-speed, photon counting applications in astronomy and how these may be substantially overcome. With careful design it is possible to operate the E2V Technologies L3CCDs at rates well in excess of that claimed by the manufacturer, and that levels of clock induced charge dramatically lower than those experienced with commercial cameras that need to operate at unity gain. Measurements of the performance of the E2V Technologies CCD201 operating at 26 MHz will be presented together with a guide to the effective reduction of clock induced charge levels. Examples of astronomical results obtained with our cameras are presented.Comment: 11 pages, 5 figure

High-resolution imaging and spectroscopy in the visible from large ground-based telescopes with natural guide stars

Near-diffraction limited imaging and spectroscopy in the visible on large (8-10 meter) class telescopes has proved to be beyond the capabilities of current adaptive optics technologies, even when using laser guide stars. The need for high resolution visible imaging in any part of the sky suggests that a rather different approach is needed. This paper describes the results of simulations, experiments and astronomical observations that show that a combination of low order adaptive optic correction using a 4-field curvature sensor and fast Lucky Imaging strategies with a photon counting CCD camera systems should deliver 20-25 milliarcsecond resolution in the visible with reference stars as faint as 18.5 magnitude in I band on large telescopes. Such an instrument may be used to feed an integral field spectrograph efficiently using configurations that will also be described.Comment: 8 pages, 3 figure

Identification of an extracellular bacterial flavoenzyme that can prevent re-polymerisation of lignin fragments

A significant problem in the oxidative breakdown of lignin is the tendency of phenolic radical fragments to re-polymerise to form higher molecular weight species. In this paper we identify an extracellular flavin-dependent dehydrolipoamide dehydrogenase from Thermobifida fusca that prevents oxidative dimerization of a dimeric lignin model compound, which could be used as an accessory enzyme for lignin depolymerisation