OBDD(Join) Proofs Cannot Be Balanced

We study OBDD-based propositional proof systems introduced in 2004 by Atserias, Kolaitis, and Vardi that prove the unsatisfiability of a CNF formula by deduction of an identically false OBDD from OBDDs representing clauses of the initial formula. We consider a proof system OBDD(?) that uses only the conjunction (join) rule and a proof system OBDD(?, reordering) (introduced in 2017 by Itsykson, Knop, Romashchenko, and Sokolov) that uses the conjunction (join) rule and the rule that allows changing the order of variables in OBDD. We study whether these systems can be balanced i.e. every refutation of size S can be reassembled into a refutation of depth O(log S) with at most a polynomial-size increase. We construct a family of unsatisfiable CNF formulas F_n such that F_n has a polynomial-size tree-like OBDD(?) refutation of depth poly(n) and for arbitrary OBDD(?, reordering) refutation ? of F_n for every ? ? (0,1) the following trade-off holds: either the size of ? is 2^?(n^?) or the depth of ? is ?(n^{1-?}). As a corollary of the trade-offs, we get that OBDD(?) and OBDD(?, reordering) proofs cannot be balanced

NetGlance NMS - An integrated network monitoring system

Mestrado de dupla diplomação com a Kuban State Agrarian UniversityThis work is about IT infrastructure and, in particular, computer networks in KubSAU and IPB. Also, it is about a network monitoring system “NetGlance NMS” developed for KubSAU System Administration Department. Work objective is to optimize the information structure for KubSAU and IPB. During the work, following tasks were completed: Research the existing IPB information structure, Compare the information structure for KubSAU and IPB, Model the IPB computer network (topology, services), Research bottlenecks and potential pitfalls in the data-center and in the computer network of IPB, Research information security mechanisms in the computer network of IPB, Organize monitoring process for the computer network in KubSAU. The most important impact of the work is an increasing network productivity and user experience as a result of creation and deploy a monitoring software.O trabalho descrito no âmbito desta dissertação incide sobre a infraestrutura TI e, em particular, sobre as redes de computadores da KubSAU e do IPB. Além disso, descreve-se um sistema de gestão integrada de redes, designada “NetGlance NMS”, desenvolvido para o Departamento de Administração de Sistemas da KubSAU. O objetivo do trabalho é desenvolver uma ferramenta para otimizar a gestão da estrutura de comunicações das duas instituições. Durante o trabalho, as seguintes tarefas foram concluídas: levantamento da estrutura de comunicações do IPB, comparação da estrutura de comunicações entre a KubSAU e o IPB, modelação da rede de comunicações do IPB (topologia, serviços), estudo de possíveis estrangulamentos no datacenter e na rede de comunicações doIPB, estudo de mecanismos de segurança na rede de comunicações do IPB, organização do processo de monitorização da rede de comunicações da KubSAU. O contributo mais relevante deste trabalho é o desenvolvimento de uma aplicação de gestão integrada de redes, de forma a contribuir para o aumento da produtividade da rede e da experiência dos utilizadores

The Meduza experiment: An orbital complex ten weeks in flight

The newspaper article discusses the contribution of space research to understanding the origin of life on Earth. Part of this basic research involves studying amino acids, ribonucleic acid and DNA molecules subjected to cosmic radiation. The results from the Meduza experiment are not all analyzed as yet. The article also discusses the psychological changes in cosmonauts as evidenced by their attitude towards biology experiments in space

TOURISM INDUSTRY STRESS INDEX AND ITS RELATIONSHIP TO THE FINANCIAL STRESS INDEX

Purpose – development of the Tourism Industry Stress Index (TSI) and the Financial Stress Index (FSI) followed by an examination of their interaction. Design – The TSI, which aggregates tourist arrivals, overnight stays and net occupancy, was tested on data for Finland, Italy, Germany and Spain between 1993 and 2020. The FSI was composed of the S&P500 index, Brent oil futures, and the real effective exchange rate of the euro. Methodology / Approach – Both stress indices were calculated as the difference between the moving standard deviation and the moving average of the monthly growth rate of the selected indicators. We aggregated them by applying two alternative techniques: arithmetic mean and non-normalized principal component analysis. The Granger causality test was utilised to assess the dependence between the indices. Findings – We identified periods of increased volatility in the European tourism market and described its connection to financial crises. The causality test of the FSI-TSI model showed that financial turmoil led to increased tourism market stress with an average lag of three months and a marginal effect of 0.2. Originality of the research – We recommend the Financial Stress Index as a predictor of the Tourism Industry Stress Index in the business cycle

Algunos razonamientos sobre el aparato formal de la mecánica clásica, relativista y cuántica

Este artículo reúne los resultados de nuestra sistematización de las magnitudes físicas y de las expresiones matemáticas de los aparatos formales de la mecánica clásica, relativista y cuántica, revelando su estructura subyacente común. La sistematización se ha realizado ordenando en tablas algunas de las magnitudes físicas y expresiones matemáticas más conocidas según sus diferentes grados de derivación, abriendo paso, de este modo, a un criterio de fundamentalidad de las leyes, principios, postulados y ecuaciones de cada aparato formal.This article contains the results of our systematization of physics’ quantities and mathematical expressions of the classic, relativistic and quantum mechanics, revealing their common underlying structure. This systematisation was realized ordering some physics’ quantities and mathematical expressions in tables according to their degree of derivation, giving a possibility for a Criterion of Fundamentality for the laws, principles, postulates and equations of each formal apparatus