Faculty of Engineering, LTH

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Digit@LTH on tour Fika Seminars

MSc. by S. Selleck: Reducing Polarization in Opinion Networks in the Presence of Stubborn Leaders

Graph polarization before and after addition of a link.


From: 2022-01-27 10:30 to 11:00
Place: Dept. of Automatic Control Seminar Room KC 3N27 and Zoom
Contact: giacomocomo [at] gmail [dot] com
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A MSc. thesis in Automatic Control will be presented.

Presenter: Samuel Selleck
Title: Reducing Polarization in Opinion Networks in the Presence of Stubborn Leaders
Examiner: Emma Tegling
Supervisors: Giacomo Como


Abstract: We study the problem of reducing polarization (variance) of opinions at stationarity in a directed weighted graph with node set divided into two groups: stubborn, initialized with a fixed opinion and regular who repeatedly update their opinion to the average of their out-neighbors, known as the DeGroot model with stubborn nodes. We show how the polarization can be minimized for a number of simple constraints, but that the problem in general is not convex. Theory is developed for the change in opinions at stationarity and the polarization measure for a rank-1 update of the network (encompassing both addition of a directed and undirected link in the network). An algorithm for optimal infinitesimal link addition is proposed, achieving a two order of magnitude reduction in complexity with respect to the number of links in the network compared to a finite difference method. Lastly variations of the algorithm together with other trivial methods of recommending a link are compared for a number of random and real networks.


Digit@LTH on tour – conceptual agenda

Since autumn of 2017 we perform a series of breakfast seminars aiming at spreading digitisation related research results at LTH.  The idea is that researchers from one of the departments EIT, Computer science, Automatic control and Math present their research at one of the other departments on a relevant level of abstraction. The objective is to strengthen our personal networks and to learn.

9.00 Fika and mingle
9.15 A senior researcher introduces a research group
9.20 An interesting research result is presented
9.35 Discussion and mingle continues

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