Lutsenko, Ie.; Protasov, I.V.
(Український математичний журнал, 2011)
Let G be a group with identity e and let I be a left-invariant ideal in the Boolean algebra PG of all subsets of G. A subset A of G is called I-thin if gA⋂A∈I for every g∈G {e}. A subset A of G is called I-sparse if, for ...