Sometimes two players avoid each other, staying away from confrontation, for as long as possible. Two commonplace occurrences in agent-vs-agent coevolutionary scenarios are loops across the vertical dimension, as seen on fig. 3.29 (left). Another strategy that attempts to stay away from the opponent is to spiral outwards from the starting position (fig. 3.29, right).
We think that this phenomenon occurs as a form of cooperation between coevolving agents: agents that agree on this behavior split the point with each other, engaging in a form of cooperation: any deviation from this behavior would be retaliated against. Figure 3.3 depicts two robots that persist on their behavior until they crash simultaneously, thus producing a tied game.
We were surprised to observe humans engaging in the same type of strategy. In
these two examples we see the human imitating the agent's behavior -- albeit
imperfectly. On the first example, H. 457 died first; but on the second, H.
259 successfully broke the pattern, and R. 370002 lost the match.