05 Mar

Seminar by Pedro Lind: “Living in a stochastic nature: a tour through interdisciplinary applications of stochastic modelling”

Tuesday, 7 March 2017, 18:30
ISCTE-IUL, Auditório 0NE03 – Mário Murteira

Living in a stochastic nature: a tour through interdisciplinary applications of stochastic modelling

Pedro Lind, University of Osnabrück
http://www.staff.uni-oldenburg.de/pedro.lind/

Abstract:
Ultimately, physics aims to uncover the laws and equations governing the evolution of one particular system. For that, one may collect a series of measurements of properties characterizing the state of one particular system. If the system is well-behaved enough, it should be possible to predict its evolution for a reasonable long time. However, if the system is “bad”-behaved, as it is typical of stochastic systems, such task may be more difficult to accomplish. In this seminar we will describe cases in physics, engineering, finance and biology where such stochastic behavior is observed and discuss in some detail ways to model particular stochastic phenomena.

19 Feb

Sofia Silva: new Master Dissertation on “An experiment about the impact of social influence on the wisdom of the crowds’ effect”

Sofia Silva presented her Master dissertation on the 20th of December 2016, at ISCTE-IUL, entitled “An experiment about the impact of social influence on the wisdom of the crowds’ effect”. The jury was composed by Luis Antunes, Jorge Louçã, and Luis Correia (supervisor).

Abstract:
Groups have the impressive ability to perform better collectively than the best of its individuals. Galton observed this first in 1907 in his ox weight experiment, but the term wisdom of the crowds (WoC) was coined only later in 2004 by Surowiecki. Cognitive diversity at the individual level enables groups to produce differentiated solutions that ultimately cluster near the true value. By cancelling out the wrongs, the aggregation method exposes the convergence of multiple local optima solutions into one, typically an averaged value that comes incredibly close to the truth-value of what is being estimating. Some accounts suggest that social influence hinders the WoC effect because it diminishes the group diversity resulting in biased outcomes. However, social influence is a naturally occurring phenomenon and it is hardly determinable the extent to which individuals are biased or independent given the complexity of the social interactions. We investigated the impact of social influence on the WoC effect by comparing the collective predictions of 4 groups regarding the number of jellybeans in a jar. We demonstrate that the group disclosing full information performs nearly as well as the control group, where no information was shared. The aggregation method to converge the estimates was the arithmetic mean showing that both groups predicted by approximately 7% the correct number. Statistical analysis has shown that diversity is not affected significantly in the social groups. We conclude that the WoC is not affected by social influence but by the degree of aggregation of the social information shared.

19 Feb

Carlos Lemos – new PhD thesis On Agent-Based Modelling of Large Scale Conflict Against a Central Authority: from Mechanisms to Complex Behaviour


Carlos Lemos presented his PhD thesis on the 16th of December 2016, at ISCTE-IUL, entitled “On Agent-Based Modelling of Large Scale Conflict Against a Central Authority: from Mechanisms to Complex Behaviour”. The jury was composed by Ernesto Costa, Francisco Santos, Pedro Magalhães, Luis Antunes, Jorge Louçã, Rui Lopes (supervisor), and Helder Coelho (co-supervisor).

Abstract:
In this work, an Agent-Based model of large scale conflict against a central authority was developed. The model proposed herein is an extension of Epstein’s Agent-Based model of civil violence, in which new mechanisms such as deprivation-dependent hardship, generalised vanishing of the risk perception (`massive fear loss’) below a critical ratio between deterrence and `group support’, legitimacy feedback, network influences and `mass enthusiasm’ (contagion) were implemented. The model was explored a set of computer experiments and the results compared with statistical analyses of events in the “Arab Spring”.

The main contributions of the present work for understanding how mechanisms of large scale conflict lead to complex behaviour were (i ) a quantitative description of the impact of the “Arab Spring” in several countries focused on complexity issues such as peaceful vs violent, spontaneous vs organized, and patterns of size, duration and recurrence of conflict events; (ii ) the explanation of the relationship between the estimated arrest probability and the size of rebellion peaks in Epstein’s model; (iii ) a new form of the estimated arrest probability with a mechanism of `massive fear loss’; (iv ) the derivation of a relationship between the legitimacy and action threshold for complex solutions to occur with both low and high values of the legitimacy; (v) a simple representation of political vs economic deprivation with a parameter which controls the `sensitivity’ to value; (vi ) the effect of legitimacy feedback; and (vii ) the effect of network influences on the stability of the solutions.



05 Jan

MOOC at FuturLearn on Big Data: Measuring and Predicting Human Behaviour

bigdata

The course covers the following topics:

What is big data?
Measuring and predicting behaviour with big data
Big data and the stock markets
Big data, crime and conflict
Big data and health
Big data and happiness
Big data, mobility and disasters

The course will also acquire some basic practical skills for data science, learning to write basic programs in R, create basic data visualisations and carry out simple analyses.

Starts 7 March, 2016.

18 Dec

Best Paper Award at IEEE WCCS’15

CarlosLemosBestPaper

Carlos Lemos, student at our doctoral program, together with his supervisors Rui Lopes and Helder Coelho, professors at our doctoral program, won the Best Paper Award at the World Conference on Complex Systems 2015, with their paper “Analysis of the Decision Rule in Epstein’s Agent-Based Model of Civil Violence”.

Congratulations to our colleagues !

01 Dec

Complex Systems Digital Campus – new Educational Resources webpage



CSDCUniTwinLogo

In the context of the knowledge map project supported by the Complex Systems Digital Campus, a new Educational Resources webpage is available, including links for open-access books, videos, conference proceedings, MOOCs, tutorials, journals, magazines, data, courses, social networks on complexity studies, and more.

Students are invited to freely use these resources.

The members of our community can also contribute to the knowledge map project by suggesting new links – please send any contribution to “Jorge.L @ iscte.pt”.


02 Oct

Open Textbook: Introduction to the Modeling and Analysis of Complex Systems

Author(s): Hiroki Sayama

Introduction to the Modeling and Analysis of Complex Systems introduces students to mathematical/computational modeling and analysis developed in the emerging interdisciplinary field of Complex Systems Science. Complex systems are systems made of a large number of microscopic components interacting with each other in nontrivial ways. Many real-world systems can be understood as complex systems, where critically important information resides in the relationships between the parts and not necessarily within the parts themselves. This textbook offers an accessible yet technically-oriented introduction to the modeling and analysis of complex systems. The topics covered include: fundamentals of modeling, basics of dynamical systems, discrete-time models, continuous-time models, bifurcations, chaos, cellular automata, continuous field models, static networks, dynamic networks, and agent-based models. Most of these topics are discussed in two chapters, one focusing on computational modeling and the other on mathematical analysis. This unique approach provides a comprehensive view of related concepts and techniques, and allows readers and instructors to flexibly choose relevant materials based on their objectives and needs. Python sample codes are provided for each modeling example.

Open PDF file here.

sayama

18 Sep

The Ecological Human

by Jennifer Dunne
Sept. 16, 2015
2015 Stanislaw Ulam Memorial Lecture Series – The Web of Life and the Ecological Human

Jennifer Dunne at SFI 2

Lecture 2 – See the video

Traditionally, most ecological research has studied ecosystems as separate from humans. In her second lecture, Dunne shows how humans fit into and impact ecosystems through their myriad interactions with other species. She then explores how the science of ecological networks can help meet the pressing need to understand the roles of humans in ecosystems, particularly in terms of resource use and consumption. With examples from pre-industrial hunter-gatherer and agricultural societies, she will explore potential lessons for modern humans in fostering a more sustainable future.

18 Sep

The Hidden Order of Complex Ecosystems

by Jennifer Dunne
Sept. 15, 2015
2015 Stanislaw Ulam Memorial Lecture Series – The Web of Life and the Ecological Human

Jennifer Dunne at SFI

Lecture 1 – See the video

Dunne shares surprising findings from her research of food webs, the networks of who eats whom in nature. After revealing hidden ecological order, she explores the underlying forces that constrain and organize ecosystems across hundreds of millions of years, from the explosion of biodiversity in the deep-time Cambrian period, long before the dinosaurs, to the deteriorating condition of ecosystems in the present day. She then describes characteristics that can fortify ecosystems against species loss and environmental change.