[AntonioLao]

Let U (the universe) denote a set of all possible spacetime events. An event E (whether a wave or a particle) is any subset of U. To say that the event E has occurred, is to say that a measurement done is a subset of two mutually exclusive disjointed sets of exact position in space and time interval of zero such that at the least the event E is associated with an element of S and an element of T.

and

In classical mechanics, an event E is denoted by the union of more than one spacetime points, which are all mutually exclusive disjointed points.



and the intersections of all points in S and T is the empty set



However, for quantum mechanics and Einstein’s relativities (SR and GR), the intersections cannot be identically zero.