-(-) пары расширений минимальных полугрупп преобразований
Perfectly supportable semigroups are σ-discrete in each Hausdorff shift-invariant topology
In this paper we introduce perfectly supportable semigroups and prove that they are σ-discrete in each Hausdorff shiftinvariant topology. The class of perfectly supportable semigroups includes each semigroup S such that FSym(X) ⊂ S ⊂ FRel(X) where FRel(X) is the semigroup of finitely supported relations on an infinite set X and FSym(X) is the group of finitely supported permutations of X.
Points extrêmaux dans un monoide affine semitopologique.
Points very close to the smallest ideal of ßS.
Polar and Ol'shanskii decompositions.
Prime ideals in a semigroup of measures
Prime properties of the smallest ideal of ßN.
Primitive idempotents in convergence semigroups
Primitive idempotents in semigroups (Research Problem #H7).
Probability measures on compact semitopological semigroups
Problems about semitopological semigroups.
Problems on semigroups and control.
Product decomposition of idempotent measures on compact semigroups
Products of threads.
Projectively Solid Sets and an N-dimensional Piccard's Theorem
We discuss functions f : X × Y → Z such that sets of the form f (A × B) have non-empty interiors provided that A and B are non-empty sets of second category and have the Baire property.
Properties of a pair of functions which generate a dense subsemigroup of S(X).
P-sets and minimal right ideals in ℕ*
Recall that a P-set is a closed set X such that the intersection of countably many neighborhoods of X is again a neighborhood of X. We show that if 𝔱 = 𝔠 then there is a minimal right ideal of (βℕ,+) that is also a P-set. We also show that the existence of such P-sets implies the existence of P-points; in particular, it is consistent with ZFC that no minimal right ideal is a P-set. As an application of these results, we prove that it is both consistent with and independent of ZFC that the shift...