On a Property of Intersection Operation in Lattices of Dominions in Quasivarieties of Abelian Groups
The dominion of a subgroup
H in a group
A (in a class
M) is the set of all elements
a ∈
A such that for all homomorphisms
φ, ψ :
A →
B ∈
M if
φ, ψ coincide on
H, then
φ(
a) =
ψ(
a). Let
A be a group,
H be a subgroup of
A,
Mi(
i ∈
I) be any quasivarieties of abelian groups and
. We find necessary and sufficient conditions when the equality
is hold.