Anonymity in Predicting the Future

Consider an arbitrary set $S$ and an arbitrary function $f : $\mathbb{R}$ \to S$\mathrm{.}Wethinkofthedomainof$f$asrepresentingtime,andforeach$x \in $\mathbb{R}$$,wethinkof$f(x)$asthestateofsomesystemattime$x$. Imagine that, at each time $x$, there is an agent who can see $f \upharpoonright (-\infty, x)$andistryingtoguess$f(x)$–in other words, the agent is trying to guess the present state of the system from its past history. In a 2008 paper, Christopher Hardin and Alan Taylor use the axiom of choice to construct a strategy that the agents can use to guarantee that, for every function $f$, all but countably many of them will guess correctly. In a 2013 monograph they introduce the idea of anonymous guessing strategies, in which the agents can see the past but don’t know where they are located in time. In this paper we consider a number of variations on anonymity. For instance, what if, in addition to not knowing where they are located in time, agents also do not know the rate at which time is progressing? What if they have no sense of how much time elapses between any two events? We show that in some cases agents can still guess successfully, while in others they perform very poorly.