Rodrigo Rey Carvalho, Vinicius de Oliveira Rodrigues·2023-12-21·via math.CO updates on arXiv.org
We prove the consistency of the existence of a $Q$-set whose square is not a $Δ$-set and that if there is a $Δ$-set, then there exists a $Δ$-set whose all finite powers are $Δ$-sets.