This is a special issue of our journal devoted to the 75th anniversary of the birth of Volodymyr Kyrychenko

ЗМІСТ

Volodymyr Kyrychenko (to the 75th anniversary)

Bondarenko V.M., Gildea J., Tylyshchak A.A., Yurchenko N.V.
On hereditary reducibility of 2-monomial matrices over commutative rings

Dudchenko I., Plakhotnyk M.
On indices and eigenvectors of quivers

Jaipong P., Tapanyo W.
Generalized classes of suborbital graphs for the congruence subgroups of the modular group

Jedlička P., Matczak K., Mućka A.
The lattice of quasivarietes of modules over a Dedekind ring

Kizmaz M.Y.
On the number of topologies on a finite set

Oliynyk A., Russyev A.
Conjugacy in finite state wreath powers of finite permutation groups

Protasov I., Protasova K.
On free vector balleans

Singh G.
Classification of homogeneous Fourier matrices

Teoh Z.Y., Teh W.C.
A Ramsey algebraic study of matrices

Tizziotti G., Villanueva J.
On certain families of sparse numerical semigroups with Frobenius number even

Visweswaran S., Vadhel P.
Planarity of a spanning subgraph of the intersection graph of ideals of a commutative ring II, Quasilocal Case

Zhuchok Y.V., Koppitz J.
Representations of ordered doppelsemigroups by binary relations