Given a set of events ${{E}}_1,{{E}}_2\ldots{{E}}_n$ defined on the sample space S such that :
(i) $\forall\, i\, and\, j,\, i\ne j,\, {{E}}_i\cap{{E}}_j=\phi$
(ii) $\begin{matrix}\overset{{n}}{\bigcup } \\ ^{i=1}\end{matrix}{{E}}_i=S$
(iii) $P({{E}}_i){\gt}0,\, \forall$
Then the events are