1. Batali, J., Kitcher, P.: Evolution of altruism in optional and compulsory games. J. Theor. Biol. 175(2), 161–171 (1995)
2. Cao, L., Ohtsuki, H., Wang, B., Aihara, K.: Evolution of cooperation on adaptively weighted networks. J. Theor. Biol. 272(1), 8–15 (2011)
3. Cardinot, M., Gibbons, M., O’Riordan, C., Griffith, J.: Simulation of an optional strategy in the prisoner’s dilemma in spatial and non-spatial environments. From Animals to Animats 14 (SAB 2016), pp. 145–156. Springer International Publishing, Cham (2016)
4. Cardinot, M., Griffith, J., O’Riordan, C.: Cyclic dominance in the spatial coevolutionary optional prisoner’s dilemma game. In: Greene, D., Namee, B.M., Ross, R. (eds.) Artificial Intelligence and Cognitive Science 2016. CEUR Workshop Proceedings, vol. 1751, pp. 33–44. Dublin, Ireland (2016)
5. Cardinot, M., O’Riordan, C., Griffith, J.: The optional prisoner’s dilemma in a spatial environment: coevolving game strategy and link weights. In: Proceedings of the 8th International Joint Conference on Computational Intelligence (IJCCI 2016), pp. 86–93 (2016)