In previous work we considered a model of a dynamically evolving network of interactions between a group of individuals, where each individual has an optimum level of social engagement with other group members. A randomly selected individual will form or break a link to obtain the required number of contacts. These interactions were formulated as a graph realisation problem. This short paper considers a game-theoretical version of the model, where individuals strategically choose the specific link to form or break. This game is known from previous work to be very complex for all but almost trivial cases, with the exception of an example with three players considered by Broom and Cannings. We revisit this example and show that even this is more complex than previously thought. In this paper, we find a general expression for the payoff functions for all possible strategy combinations. In addition to the three Nash equilibria previously found, we find a set of six more. The considerations of all possibilities proves to be infeasible, leaving the possibility of more solutions open.
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Figure 1. Transition graph of the sequence 111 showing the minimal set in every possible move at each of the six vertices. Vertex 1 represents the sequence 211, i.e. individual $ v_{1} $ is the one in deficit and moves clockwise to sequence 101 with probability $ \frac{p_1}{3} $ and anticlockwise to 110 with probability $ \frac{1-p_1}{3} $, it will stay in the same state with probability $ \frac{2}{3} $. Similarly, vertex 2 represents sequence 101, vertex 3 represents sequence 112, vertex 4 represents sequence 011, vertex 5 represents sequence 121 and vertex 6 represents sequence 110.
Figure 3. Transition graph of the sequence 111 showing the first solution of the cyclic set, solution 4: Straight arrows $ \searrow $: when $ p_i = 1 $, individual $ v_i $ will move clockwise. Straight arrows $ \nwarrow $:when $ p_i = 0 $, individual $ v_i $ will move anti-clockwise. Curved arrows: for $ 0<p_i<1 $ the movement of individual $ v_i $ to the next state could happen in either direction, clockwise with probability $ p_i $ or anti-clockwise with probability $ 1-p_i $.
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Transition graph of the sequence 111 showing the minimal set in every possible move at each of the six vertices. Vertex 1 represents the sequence 211, i.e. individual
Transition graph of the sequence 111 showing the minimal set in every possible move at each of the six vertices. Vertex
Transition graph of the sequence 111 showing the first solution of the cyclic set, solution 4: Straight arrows