It is easy to see that the sets E i {\displaystyle E_{i}} are pairwise disjoint and E 1 ∪ E 2 ∪ ⋯ = B {\displaystyle E_{1}\cup E_{2}\cup \cdots =B} .
On helposti nähtävissä, että joukot E i {\displaystyle E_{i}} ovat pistevieraita ja E 1 ∪ E 2 ∪ … = B {\displaystyle E_{1}\cup E_{2}\cup \ldots =B} .