Published online by Cambridge University Press: 12 March 2014
Let  be a finite sequence of algebras of sets given on a set
 be a finite sequence of algebras of sets given on a set 
 with more than
 with more than  pairwise disjoint sets not belonging to
 pairwise disjoint sets not belonging to  It was shown in [4] and [5] that in this case
 It was shown in [4] and [5] that in this case  Let us consider, instead
 Let us consider, instead  a finite sequence of algebras
 a finite sequence of algebras  It turns out that if for each natural i ≤ l there exist no less than
 It turns out that if for each natural i ≤ l there exist no less than  pairwise disjoint sets not belonging to
 pairwise disjoint sets not belonging to  then
 then  But if l ≥ 195 and if for each natural i ≤ l there exist no less than
 But if l ≥ 195 and if for each natural i ≤ l there exist no less than  pairwise disjoint sets not belonging to
 pairwise disjoint sets not belonging to  then
 then  After consideration of finite sequences of algebras, it is natural to consider countable sequences of algebras. We obtained two essentially important theorems on a countable sequence of almost σ-algebras (the concept of almost σ-algebra was introduced in [4]).
 After consideration of finite sequences of algebras, it is natural to consider countable sequences of algebras. We obtained two essentially important theorems on a countable sequence of almost σ-algebras (the concept of almost σ-algebra was introduced in [4]).