What is a full event group?

Question

Probability theory

I found two types of definitions - from the wiki, for example, it is
"a system of random events such that as a result of a random experiment one and only one of them will certainly happen ."
and in other sources one comes across
"a system of random events such that as a result of a random experiment performed it will certainly happen one of them is "

That is, in the second there is no addition" and only one ", although, as for me, this is a fundamentally important point.
Suppose such a system
of Kp, Kb, Kt, Kch
(K - card, p, b, t, h - spades, diamonds, etc.) is complete, because exactly one and only one can happen here.

But the system
Kp, Kb, Kt, Kch, K7
(7 - seven) is complete or not?
If according to the first definition, then the idea is not. After all, the seven has some kind of suit, which means that two events have occurred.
And if according to the second, then it turns out that it is.

Seven is like a "sub-event" of the other four. That is, in the end, "full" is "full" without unnecessary "" or what?

Answer 1

Events in a complete group must be incompatible and opposite .
In the case of suits, the group is complete. Either a club fell out, or NOT a club. Inconsistency - if a club fell out, then no other three fell out.
In the second case, everything depends on the problem statement. If you "complete" the task with suits, then the loss of a seven violates the principle of incompatibility: it can be of any suit. The group is incomplete.