The principle of unique location
For all things, for all locations y, for all locations z and for all times t, that a thing is in location y at time t and that y is not identical to z logically implies that that thing is not in location z at time t.
(∀x)(∀y)(∀z)(∀t)((Lxyt∧x≠y)⇒¬Lxzt)
Idea
The principle is meant to capture the common sense idea that if something is somewhere, then it is not somewhere else. It cannot be two places at one:
(∀x)(∀y)(∀z)(∀t)¬◊(Lxyt∧Lxzt∧x≠y)