a1 University of Gdańsk, Institute of Mathematics, Wita Stwosza 57, 80-952 Gdańsk, Poland, E-mail: [email protected]
a2 Institute of Mathematics, WSRP, 08-110 Siedlce, Poland, E-mail: [email protected]
We prove the following theorems:
1. If X ⊆ 2 ω is a γ-set and Y ⊆2 ω is a strongly meager set, then X + Y is Ramsey null.
2. If X ⊆2 ω is a γ-set and Y belongs to the class of sets, then the algebraic sum X + Y is an set as well.
3. Under CH there exists a set X ∈ MGR* which is not Ramsey null.
(Received October 02 1999)
(Revised February 23 2001)
Key words and phrases
† Partially supported by the KBN grant 2 P03A 047 09.