I will write on one of the rules weakness by my understanding.
By my understanding we have two reasons for agent became dead:
- reach the top
- nowhere to move (it mean the other molecules is surrounded by agent )
imagine we are lucky and we have the accumulation. Inside accumulation molecules cannot move.
But… the upper layer of the accumulation is not surrounded by molecules, so it can “evaporate upwards”, after time, layer by layer accumulation can “evaporate”.
Ok… I think we have rule- if agent is dead- it moves no longer
But imagine that our accumulation is in the initial stage and its molecules is “almost dead”- their have still somewhere to move. So above said is still valid.
I think extreme values of environment signal should stop the movement (like new rule).
so there was some thoughts in my not fluent English