Well, if you assume these agents do not employ time-discounting then you indeed cannot compare trajectories, since all of them might have infinite utility (and are computationally intractable as you say) if they don’t terminate.
We do run into the same problem if we assume realistic action spaces, i.e. consider all the things we could possibly do, as there are too many even for a single time step.
RL algorithms “solve” this by working with constrained action spaces and discounting future utility.. and also by often having terminating trajectories.
Humans also work on (highly) constrained action spaces and have strong time discounting [citation needed], and every model of a rational human should take that into account.
I admit those points are more like hacks we’ve come up with for practical situations, but I suppose the computational intractability is a reason why we can’t already have all the nice things ;-)
Well, if you assume these agents do not employ time-discounting then you indeed cannot compare trajectories, since all of them might have infinite utility (and are computationally intractable as you say) if they don’t terminate.
We do run into the same problem if we assume realistic action spaces, i.e. consider all the things we could possibly do, as there are too many even for a single time step.
RL algorithms “solve” this by working with constrained action spaces and discounting future utility.. and also by often having terminating trajectories. Humans also work on (highly) constrained action spaces and have strong time discounting [citation needed], and every model of a rational human should take that into account.
I admit those points are more like hacks we’ve come up with for practical situations, but I suppose the computational intractability is a reason why we can’t already have all the nice things ;-)