Some variation on the Riemann derangement theorem
Roman Wituła, Edyta Hetmaniok, Damian Słota
On Commutation Properties of the Composition Relation of Convergent and Divergent Permutations (Part I)
Roman Wituła, Edyta Hetmaniok, Damian Słota
On Certain Approximation Problem Connected with the Sums of Subseries
Roman Wituła, Konrad Kaczmarek, Edyta Hetmaniok, Damian Słota