title: Avoiding or restricting defectors in public goods games?
abstract: When creating a public good, strategies or mechanisms are required to handle defectors. We first show mathematically and numerically that prior agreements with posterior compensations provide a strategic solution that leads to substantial levels of cooperation in the context of public goods games, results that are corroborated by available experimental data. Notwithstanding this success, one cannot, as with other approaches, fully exclude the presence of defectors, raising the question of how they can be dealt with to avoid the demise of the common good. We show that both avoiding creation of the common good, whenever full agreement is not reached, and limiting the benefit that disagreeing defectors can acquire, using costly restriction mechanisms, are relevant choices. Nonetheless, restriction mechanisms are found the more favourable, especially in larger group interactions. Given decreasing restriction costs, introducing restraining measures to cope with public goods free-riding issues is the ultimate advantageous solution for all participants, rather than avoiding its creation.
authors.affiliation: AI lab, Computer Science Department, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium MLG, Département d'Informatique, Université Libre de Bruxelles, Boulevard du Triomphe CP212, 1050 Brussels, Belgium School of Computing, Teesside University, Borough Road, Middlesbrough TS1 3BA, UK t.han@tees.ac.uk.
authors.forename: The Anh
authors.identifier: http://orcid.org/0000-0002-3095-7714
authors.initials: TA
authors.lastname: Han
authors.affiliation: Centro de Inteligência Artificial (CENTRIA), Departamento de Informática, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Luís Moniz
authors.identifier: http://orcid.org/0000-0001-7880-4322
authors.initials: LM
authors.lastname: Pereira
authors.affiliation: AI lab, Computer Science Department, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium MLG, Département d'Informatique, Université Libre de Bruxelles, Boulevard du Triomphe CP212, 1050 Brussels, Belgium tom.lenaerts@ulb.ac.be.
authors.forename: Tom
authors.identifier: http://orcid.org/0000-0003-3645-1455
authors.initials: T
authors.lastname: Lenaerts
mesh_terms: D005717:Games, Experimental; D006801:Humans; D008962:Models, Theoretical
keywords: commitment; cooperation; evolutionary games; public goods