Ron Peretz

Thematic seminars
Economic theory seminar

Ron Peretz

Bar Ilan University
Robust naïve learning in social networks

IBD Salle 16

Îlot Bernard du Bois - Salle 16

5-9 boulevard Maurice Bourdet
13001 Marseille

Thursday, March 31 2022| 12:00pm to 1:00pm

Gaëtan Fournier: gaetan.fournier[at]
Evgeny Tsodikovich: evgeny.tsodikovich[at]


We study a model of opinion exchange in social networks where a state of the world is realized and every agent receives a zero-mean noisy signal of the realized state. It is known from Golub and Jackson that under DeGroot dynamics agents reach a consensus that is close to the state of the world when the network is large. The DeGroot dynamics, however, is highly non-robust and the presence of a single "stubborn agent" that does not adhere to the updating rule can sway the public consensus to any other value. We introduce a variant of DeGroot dynamics that we call 1/m-DeGroot. 1/m-DeGroot dynamics approximates standard DeGroot dynamics to the nearest rational number with m as its denominator and like the DeGroot dynamics it is Markovian and stationary. We show that in contrast to standard DeGroot dynamics, 1/m-DeGroot dynamics is highly robust both to the presence of stubborn agents and to certain types of misspecifications.