Browsing 2019 by Issue Date

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  • CI-property for the group (Zp) 2 × Zq × Zr Eskander Ali and Ahed Hassoon 
    Subbotin, I. Y. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    In this paper we prove that the group (Zp) 2 × Zq ×Zr is CI-group, where p, q, r are primes such that q and r divide p − 1, and r divides q − 1.
  • Representations of ordered doppelsemigroups by binary relations 
    Zhuchok, Yu .V.; Koppitz, J. (2019)
    We extend the study of doppelsemigroups and introduce the notion of an ordered doppelsemigroup. We construct the ordered doppelsemigroup of binary relations on an arbitrary set and prove that every ordered doppelsemigroup ...
  • Automorphism groups of superextensions of finite monogenic semigroups 
    Banakh, T.; Gavrylkiv, V. (2019)
    A family L of subsets of a set X is called linked if A ∩ B 6= ∅ for any A, B ∈ L. A linked family M of subsets of X is maximal linked if M coincides with each linked family L on X that contains M. The superextension ...
  • Gram matrices and Stirling numbers of a class of diagram algebras 
    B i, N . K.; Parvathi, M . (2019)
    In this paper, we introduce Gram matrices for the signed partition algebras, the algebra of Z2-relations and the par- tition algebras. The nondegeneracy and symmetic nature of these Gram matrices are establised. ...
  • On certain families of sparse numerical semigroups with Frobenius number even 
    Tizziotti, G.; Villanueva, j. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    This paper is about sparse numerical semigroups and applications in the Weierstrass semigroups theory. We describe and find the genus of certain families of sparse numerical semigroups with Frobenius number even and we ...
  • Exact sequences of graphs Ahmad Abbasi and Ali Ramin 
    Protasov, I. V. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    In this paper, exact sequences of graphs are defined and investigated. Considering some functors on the category of graphs, we study some conditions to determine exactness of functors.
  • A Ramsey algebraic study of matrices 
    Teoh, Z .Y.; Teh, W.C. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    The notion of a topological Ramsey space was introduced by Carlson some 30 years ago. Studying the topological Ramsey space of variable words, Carlson was able to derive many classical combinatorial results in a unifying ...
  • Conjugacy in finite state wreath powers of finite permutation groups 
    liynyk, A . O; Russyev, A . (2019)
    It is proved that conjugated periodic elements of the infinite wreath power of a finite permutation group are conjugated in the finite state wreath power of this group. Counterexamples for nonperiodic elements are given.
  • Solutions of the matrix linear bilateral polynomial equation and their structure 
    Dzhaliuk, N.S .; Petrychkovych, V.M . (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    We investigate the row and column structure of solutions of the matrix polynomial equation A(λ)X(λ) + Y (λ)B(λ) = C(λ), where A(λ), B(λ) and C(λ) are the matrices over the ring of poly- nomials F[λ] with coefficients ...
  • On cospectral signed digraphs 
    Bhat, M. A.; Naikoo, T. A.; Pirzada, S. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    The set of distinct eigenvalues of a signed digraph S together with their respective multiplicities is called its spectrum. Two signed digraphs of same order are said to be cospectral if they have the same spectrum. In ...
  • On hereditary reducibility of 2-monomial matrices over commutative rings 
    Bondarenko, V. M.; Gildea, J.; Tylyshchak, A. A.; Yurchenko, N.V. (2019)
    A 2-monomial matrix over a commutative ring R is by definition any matrix of the form M(t, k, n) = Φ Ik 0 0 tIn−k , 0 < k < n, where t is a non-invertible element of R, Φ the companion matrix to λ n − 1 and Ik ...
  • The lattice of quasivarietes of modules over a Dedekind ring 
    Jedlička, P.; Matczak, K .; Mućka, A . (2019)
    In 1995 D. V. Belkin described the lattice of quasivarieties of modules over principal ideal domains [1]. The following paper provides a description of the lattice of subquasivarieties of the variety of modules over a given ...
  • On the Fitting ideals of a multiplication module 
    Hadjirezaei, S.; Karimzadeh, S. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    In this paper, we characterize all finitely gene- rated multiplication R-modules whose the first nonzero Fitting ideal of them is contained in only finitely many maximal ideals. Also, we prove that a finitely generated ...
  • On indices and eigenvectors of quivers 
    Dudchenko, I .; lakhotnyk, M.P. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    We study formulas for eigenvectors of strongly connected simply laced quivers in terms of eigenvalues. The relation of these formulas to the isomorphism of quivers is investigated.
  • On free vector balleans 
    Protasov, I.; Protasova, K. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    A vector balleans is a vector space over R en- dowed with a coarse structure in such a way that the vector opera- tions are coarse mappings. We prove that, for every ballean (X, E), there exists the unique free vector ...
  • Generalized classes of suborbital graphs for the congruence subgroups of the modular group 
    Jaipong, P.; Tapanyo, W. (2019)
    Let Γ be the modular group. We extend a non-trivial Γ-invariant equivalence relation on Qb to a general relation by replacing the group Γ0(n) by ΓK(n), and determine the suborbital graph F K u,n, an extended concept of ...
  • Representations of strongly algebraically closed algebras A. Molkhasi and K. P. Shum 
    Simson, D. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    We introduce the notion of q′-compactness for MV-algebras. One of the main results of the paper is a characterization of a class of orthomodular lattices that are horizontal sums of strongly algebraically closed algebras.
  • On the lattice of cyclic codes over finite chain rings 
    Fotue -Tabue, A .; Mouaha, C. (2019)
    In this paper, R is a finite chain ring of invariants (q, s), and l is a positive integer fulfilling gcd(l, q) = 1. In the language of q-cyclotomic cosets modulo l, the cyclic codes over R of length l are uniquely decomposed ...
  • Paley-type graphs of order a product of two distinct primes 
    Das, A . (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    In this paper, we initiate the study of Paley-type graphs ΓN modulo N = pq, where p, q are distinct primes of the form 4k + 1. It is shown that ΓN is an edge-regular, symmetric, Eulerian and Hamiltonian graph. Also, the ...
  • On the zero forcing number of graphs and their splitting graphs 
    Chacko, B.; Dominic, C.; Premodkumar, K. P. (ДЗ "ЛНУ імені Тараса Шевченка", 2019)
    In [10], the notion of the splitting graph of a graph was introduced. In this paper we compute the zero forcing number of the splitting graph of a graph and also obtain some bounds besides finding the exact value of ...

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