Mercoledì 14 maggio, ore 15

Aula riunioni IAC - 1 piano,

Via dei Taurini 19, Roma

Alberto Saracco (Università di Parma)

Fighting Gerrymandering: a discrete approach.

Abstract: Whenever an election is run dividing the population into electoral districts, each based on winner-takes-all, the Gerrymangdering phenomenon appears. Over 2 centuries ago, Massachusetts' Governor Gerry modified the boundaries of his own ellectoral district in order to assure his re-election. Indeed, whenever two parties (or candidates) run for an election, if one of them has more then one third of the votes, the electoral districts can be shaped in order to assure its electoral win. Thus a double-faced problem arises: on one hand a method is needed to measure how gerrymandered a district is; on the other hand it would be useful to have an objective method to shape districts and avoiding the possibility of gerrymandering. A great part of the mathematical studies on the problem have been devoted either to geometrical propertiesof the district or on the application of the theory of isoperimetrical problems in this area. Recently it has been pointed out that it would be more realistic a discrete geometry approach, based on graphs and nets. In this talk I will present a discrete districting plan proposed by Giorgio Saracco and myself and analyse its properties.