SEMCIÊNCIA

Multimode Control Attacks on Elections Piotr Faliszewski ,  Edith Hemaspaandra ,  Lane A. Hemaspaandra (Submitted on 11 Jul 2010) In 1992, Bartholdi, Tovey, and Trick opened the study of control attacks on elections---attempts to improve the election outcome by such actions as adding/deleting candidates or voters. That work has led to many results on how algorithms can be used to find attacks on elections and how complexity-theoretic hardness results can be used as shields against attacks. However, all the work in this line has assumed that the attacker employs just a single type of attack. In this paper, we model and study the case in which the attacker launches a multipronged (i.e., multimode) attack. We do so to more realistically capture the richness of real-life settings. For example, an attacker might simultaneously try to suppress some voters, attract new voters into the election, and introduce a spoiler candidate. Our model provides a unified framework for such varied attacks, ...

Por que a maior parte dos blogueiros de ciência e céticos são Popperianos? Kuhn é muito melhor, e pode ser modelado pela sociophysics... Highly connected - a recipe for success Authors: Krzysztof Suchecki, Andrea Scharnhorst, Janusz A. Holyst (Submitted on 5 Jul 2010 (v1), last revised 6 Jul 2010 (this version, v2)) Abstract: In this paper, we tackle the problem of innovation spreading from a modeling point of view. We consider a networked system of individuals, with a competition between two groups. We show its relation to the innovation spreading issues. We introduce an abstract model and show how it can be interpreted in this framework, as well as what conclusions we can draw form it. We further explain how model-derived conclusions can help to investigate the original problem, as well as other, similar problems. The model is an agent-based model assuming simple binary attributes of those agents. It uses a majority dynamics (Ising model to be exact), meaning that individuals attemp...

The Shield that Never Was: Societies with Single-Peaked Preferences are More Open to Manipulation and Control P. Faliszewski ,  E. Hemaspaandra ,  L. A. Hemaspaandra ,  J. Rothe (Submitted on 17 Sep 2009 ( v1 ), last revised 19 Jun 2010 (this version, v2)) Much work has been devoted, during the past twenty years, to using complexity to protect elections from manipulation and control. Many results have been obtained showing NP-hardness shields, and recently there has been much focus on whether such worst-case hardness protections can be bypassed by frequently correct heuristics or by approximations. This paper takes a very different approach: We argue that when electorates follow the canonical political science model of societal preferences the complexity shield never existed in the first place. In particular, we show that for electorates having single-peaked preferences, many existing NP-hardness results on manipulation and control evaporate. Comments: 38 pages, 2 figures Subjects: Com...

Eu duvido que esses modelos Poissonianos funcionem, mas fica  como referencia:  http://arxiv.org/abs/1004.2003  The Socceral Force  Norbert Bátfai  (Submitted on 12 Apr 2010 (v1), last revised 22 Apr 2010 (this  version, v2))  We have an audacious dream, we would like to develop a  simulation and virtual reality system to support the decision  making in European football (soccer). In this review, we  summarize the efforts that we have made to fulfil this dream  until recently. In addition, an introductory version of FerSML  (Footballer and Football Simulation Markup Language) is  presented in this paper.  Comments: 20 pages, 13 figures, added FerSML 0.0.2  Subjects: Artificial Intelligence (cs.AI); Software  Engineering (cs.SE)  MSC classes: 68T35  ACM classes: H.5.1  Cite as: arXiv:1004.2003v2 [cs.AI]  http://arxiv.org/abs/1002.0797  Soccer: is scoring goals a predictable Poissonian process?  Andreas Heuer, Christian Mueller, Oliver Rubner  (Submitted on 3 Feb 2010 (v1), last revised ...

Em termos de esportes, é bem conhecida a fascinação dos americanos por estatísticas. Neste blog do New York Times você pode encontrar dados estatísticos minuto a minuto das partidas da Copa.  Muito interessante... para um físico estatístico. Idéia para um paper: claramente as estatísticas para intervalos entre posse de bola, chutes a gol, escanteios e faltas não seguem uma distribuição de Poisson, mas lembram uma distribuição com lei de potência (com cut-off de 45 min, claro!) ou talvez uma log-normal. Para um exemplo, veja as estatísticas do jogo Uruguai vs França aqui . Dá para entender algo disso: a probabilidade de um escanteio seguir outro é alta e, quando um time está pressionando outro, os chutes a gol podem sair em sequência (não está claro a origem da distribuição não uniforme de faltas). Na verdade, existem boas razões para se acreditar que o jogo de futebol não é Markoviano nem estacionário. Mas então, seria possível modelar (gerar) essas distribuições de modo simples? Idéi...

Sociophysics http://www.eoht.info/page/Sociophysics In science , sociophysics is the study of social phenomena from a physics perspective. The subject seems to deal with thermodynamics in part; albeit, the majority of theories in this field seem to be on statistical extrapolations or phase transition models. A noted researcher in the field is physicist Serge Galam claims that he has been in the field of sociophysics since the late 1970s. [1] A noted researcher in this field is Canadian political scientist Paris Arnopoulos and his 1993 book Sociophysics, in which he speculates on heat, pressure, temperature, entropy, and volumes of societies. [3] At the 2008 international workshop on socio physics, at Torino, Italy, the focus was on the statistical physics modeling of large scale social phenomena, such as opinion formation, cultural dissemination, the origin and evolution of language, crowd behavior, social contagion; where it was stated that previous years had witnessed the atte...

É uma estranha coincidência que o livro de Charles Galton Darwin ( The Next Million Years ) tenha surgido quase simultaneamente com o clássico Fundação de Isaac asimov. Será que houve influência mútua? Update: Parece que Darwin leu Asimov, pois os contos foram publicados a partir de 1942: Foundation was originally a series of eight short stories published in Astounding Magazine between May 1942 and January 1950. According to Asimov, the premise was based on ideas set forth in Edward Gibbon 's History of the Decline and Fall of the Roman Empire , and was invented spontaneously on his way to meet with editor John W. Campbell , with whom he developed the concept. [2] Original trilogy The first four stories were collected, along with a new story taking place before the others, in a single volume published by Gnome Press in 1951 as Foundation . The remainder of the stories were published in pairs as Foundation and Empire (1952) and Second Foundation (1953), resulting in the ...

A recente queda do IBOVESPA de 19.9% desde seu record histórico foi prevista por Didier Sornette? Wednesday, June 02, 2010 Econophysicist Accurately Forecasts Gold Price Collapse The first results from the Financial Bubble Experiment will have huge implications for econophysics There are good reasons to think that stock markets are fundamentally unpredictable. Many econophysicists believe for example, that the data from these markets bear a startling resemblance to other data from seemingly unconnected phenomena, such as the size of earthquakes, forest fires and avalanches, which defy all efforts of prediction.  Some go as far as to say that these phenomena are governed by the same fundamental laws so that if one is unpredictable, then they all are.  And yet financial markets may be different. Last year, this blog covered an extraordinary forecasts made by Didier Sornette at the Swiss Federal Institute of Technology in Zurich, who declared that the Shanghia Composite Index was a bubble...

The Next Million Years In famous publication , The Next Million Years is a 1952 book written by C.G. Darwin notable as being the first-ever published document outlining a theory using the terms " human thermodynamics " and " human molecule " in unison. [1] Original copies sell for as much as $395 dollars. The book was reprinted in 1953 and 1973. The Next Million Years is one of the founding books in the history of human thermodynamics . OverviewIn short, Darwin argued that humans were molecules, that assemblies of humans constituted "conservative dynamical systems", and that one could use statistical thermodynamics , particularly American mathematical physicist Willard Gibbs version of it, to predict the course of the next million years of human evolution . In his book, according to a 1953 review by Time magazine, Darwin, a theoretical physicist, invades sociological territory where many sociologists fear to tread. [2] He bases his reasoning about man...

Social physics In science , social physics is the study of social systems and social phenomena from the perspective of physics . History The term social physics was first introduced by Belgian statistician Adolphe Quetelet in his 1835 book Essay on Social Physics: Man and the Development of his Faculties, in which he outlines the project of a social physics and describes his concept of the "average man" (l'homme moyen) who is characterized by the mean values of measured variables that follow a normal distribution and collects data about many such variables. [5] When French social philosopher Auguste Comte , who had also used the term social physics, in his 1842 work, discovered that Quetelet had appropriated the term 'social physics' prior to him, Comte found it necessary to invent the term 'sociologie' (sociology) because he disagreed with Quetelet's collection of statistics. Comte defined social physics as the study of the laws of society or the s...

Parodiando Engels, "todo economista vivo é escravo de um físico morto". A questão não é se novas idéias e conceitos físicos podem ser aplicados às ciências econômicas e sociais, mas por que os velhos conceitos da física newtoniana ("equilíbrio", "forças" econômicas, "tensão" social etc.) permanecem no discurso sócio-econômico. The (unfortunate) complexity of the economy Jean-Philippe Bouchaud (Submitted on 6 Apr 2009) This article is a follow-up of a short essay that appeared in Nature 455, 1181 (2008) [ arXiv:0810.5306 ]. It has become increasingly clear that the erratic dynamics of markets is mostly endogenous and not due to the rational processing of exogenous news. I elaborate on the idea that spin-glass type of problems, where the combination of competition and heterogeneities generically leads to long epochs of statis interrupted by crises and hyper-sensitivity to small changes of the environment, could be metaphors for the complexity of ec...

Quando Tiago estava trabalhando em seu mestrado, ele veio para a LASCON - Latin American School of Computational Neuroscience, em julho de 2008. Na cantina do Walter, Roque lembra que discutimos a questão do subsampling em sistemas críticos (inclusive com esta palavra). Sugeri ao Tiago que fizesse uma simulação em um sistema simples (por exemplo, a rede aleatória excitável que Mauro e eu trabalhamos em 2006, o modelo OFC (que tem relações com modelos de neurônios integra dispara) ou mesmo um modelo de pilha de areia tradicional. Alguns meses mais tarde, Chialvo deu a mesma idéia para Tiago e Mauro (e fez questão de anotar em um guardanapo a a idéia, a data e as pessoas presentes, e pediu para todos assinarem!). Não sei se ele usou a palavra subsampling , acredito que sim. Desta vez, Tiago acreditou na idéia (o meu problema é que santo de casa não faz milagre...) e fez as simulações. Batata: subsampling em sistemas críticos gera distribuições que fogem às leis de potência, ficam mais pa...

Biology, Sociology, Geology by Computational Physicists (Monograph Series on Nonlinear Science and Complexity) Stauffer, Dietrich, Oliveira, Suzana Moss de, Oliveira, Paulo Murilo Castro de and Martins, Jorge Simoes de Sa Elsevier: Amsterdam, 2006 ISBN 0444521461 (pb) Comprar aqui . Reviewed by Frank Schweitzer and Markus Geipel ETH Zurich, Switzerland "Physicists pretend not only to know everything, but also to know everything better. This applies in particular to computational statistical physicists like us". These are the very first two sentences of the book reviewed here. In a nutshell, the authors point the reader at their position on approaching phenomena as diverse as biological aging and speciation (chapters 3, 4), languages (chapter 5) or earthquakes (chapter 7). What is special about Biology, Sociology, Geology by Computational Physicists? First of all the fact that the authors approach these topics without the burden of frameworks and know how, immanent to these d...

A dar uma olhada. Isso parece contar a história da polarização ideológica nos EUA e uma polarização similar, em menor escala, no Brasil. Hate: no choice. Agent simulations Krzysztof Kulakowski , Malgorzata J. Krawczyk , Przemyslaw Gawronski (Submitted on 19 Aug 2009) We report our recent simulations on the social processes which -- in our opinion -- lie at the bottom of hate. First simulation deals with the so-called Heider balance where initial purely random preferences split the community into two mutually hostile groups. Second simulation shows that once these groups are formed, the cooperation between them is going to fail. Third simulation provides a numerical illustration of the process of biased learning; the model indicates that lack of objective information is a barrier to new information. Fourth simulation shows that in the presence of a strong conflict between communities hate is unavoidable. Comments: 17 pages, 5 figures Subjects: Physics and Society (physics.soc-ph) Cite ...

Guerras modelaram altruísmo humano, dizem pesquisadores RICARDO BONALUME NETO da Folha de S.Paulo A guerra na Pré-História era frequente e altamente letal, mas essa luta constante está ligada ao surgimento de comportamentos altruístas na espécie humana. E quando os grupos humanos atingiram determinado tamanho, criava-se o potencial para uma revolução no comportamento e na cultura. É o que indicam dois estudos publicados na edição de hoje da revista científica "Science". José Manuel Ribeiro/Reuters Figura de 10 mil anos com cavalos copulando é uma das primeiras que dão a ideia de movimento, afirmam pesquisadores em artigos Samuel Bowles, do Instituto Santa Fé (EUA) e da Universidade de Siena (Itália), usou dados arqueológicos e etnográficos sobre populações de caçadores-coletores e mostrou que a mortalidade produzida pelos conflitos poderia ter promovido a predisposição para ajudar membros de grupos não diretamente aparentados. O guerreiro "altruísta" é aquele que es...