ISSN 1937 - 1055 VOLUME 4, 2017 INTERNATIONAL JOURNAL OF MATHEMATICAL COMBINATORICS EDITED BY THE MADIS OF CHINESE ACADEMY OF SCIENCES AND ACADEMY OF MATHEMATICAL COMBINATORICS & APPLICATIONS, USA December, 2017 Vol.4, 2017 ISSN 1937-1055 International Journal of Mathematical Combinatorics (www.mathcombin.com) Edited By The Madis of Chinese Academy of Sciences and Academy of Mathematical Combinatorics & Applications, USA December, 2017 Aims and Scope: The International J.Mathematical Combinatorics (ISSN 1937-1055) is a fully refereed international journal, sponsored by the MADIS of Chinese Academy of Sci- ences and published in USA quarterly comprising 110-160 pages approx. per volume, which publishes original research papers and survey articles in all aspects of Smarandache multi-spaces, Smarandache geometries, mathematical combinatorics, non-euclidean geometry and topology and their applications to other sciences. Topics in detail to be covered are: Smarandache multi-spaces with applications to other sciences, such as those of algebraic multi-systems, multi-metric spaces, , etc.. Smarandache geometries; · · · Topological graphs; Algebraic graphs; Random graphs; Combinatorial maps; Graph and map enumeration; Combinatorial designs; Combinatorial enumeration; Differential Geometry; Geometry on manifolds; Low Dimensional Topology; Differential Topology; Topology of Manifolds; Geometrical aspects of Mathematical Physics and Relations with Manifold Topology; Applications of Smarandache multi-spaces to theoretical physics; Applications of Combi- natorics to mathematics and theoretical physics; Mathematical theory on gravitational fields; Mathematical theory on parallel universes; Other applications of Smarandache multi-space and combinatorics. Generally, papers on mathematics with its applications not including in above topics are also welcome. 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Subscription A subscription can be ordered by an email directly to Prof.Linfan Mao PhD The Editor-in-Chief of International Journal of Mathematical Combinatorics Chinese Academy of Mathematics and System Science Beijing, 100190, P.R.China Email: [email protected] Price: US$48.00 Editorial Board (4th) Editor-in-Chief Linfan MAO Shaofei Du Chinese Academy of Mathematics and System Capital Normal University, P.R.China Science, P.R.China Email: [email protected] and Xiaodong Hu Academy of Mathematical Combinatorics & Chinese Academy of Mathematics and System Applications, USA Science, P.R.China Email: [email protected] Email: [email protected] Deputy Editor-in-Chief Yuanqiu Huang Hunan Normal University, P.R.China Guohua Song Email: [email protected] Beijing University of Civil Engineering and H.Iseri Architecture, P.R.China Mansfield University, USA Email: [email protected] Email: hiseri@mnsfld.edu Editors Xueliang Li Nankai University, P.R.China Arindam Bhattacharyya Email: [email protected] Jadavpur University, India Guodong Liu Email: [email protected] Huizhou University Said Broumi Email: [email protected] Hassan II University Mohammedia W.B.Vasantha Kandasamy Hay El Baraka Ben M’sik Casablanca Indian Institute of Technology, India B.P.7951 Morocco Email: [email protected] Junliang Cai Ion Patrascu Beijing Normal University, P.R.China Fratii Buzesti National College Email: [email protected] Craiova Romania Yanxun Chang Han Ren Beijing Jiaotong University, P.R.China East China Normal University, P.R.China Email: [email protected] Email: [email protected] Jingan Cui Ovidiu-Ilie Sandru Beijing University of Civil Engineering and Politechnica University of Bucharest Architecture, P.R.China Romania Email: [email protected] ii International Journal of Mathematical Combinatorics Mingyao Xu Peking University, P.R.China Email: [email protected] Guiying Yan Chinese Academy of Mathematics and System Science, P.R.China Email: [email protected] Y. Zhang Department of Computer Science Georgia State University, Atlanta, USA Famous Words: The greatest lesson in life is to know that even fools are right sometimes. By Winston Churchill, a British statesman. International J.Math. Combin. Vol.4(2017), 1-18 Direct Product of Multigroups and Its Generalization P.A. Ejegwa (Department of Mathematics/Statistics/Computer Science, University of Agriculture, P.M.B. 2373, Makurdi, Nigeria) A. M. Ibrahim (Department of Mathematics, Ahmadu Bello University, Zaria, Nigeria) E-mail: [email protected], [email protected] Abstract: This paper proposes the concept of direct product of multigroups and its gen- eralization. Some results are obtained with reference to root sets and cuts of multigroups. We prove that the direct product of multigroups is a multigroup. Finally, we introduce the notion of homomorphism and explore some of its properties in the context of direct product of multigroups and its generalization. Key Words: Multisets, multigroups, direct product of multigroups. AMS(2010): 03E72, 06D72, 11E57, 19A22. §1. Introduction In set theory, repetition of objects are not allowed in a collection. This perspective rendered set almost irrelevant because many real life problems admit repetition. To remedy the handicap in the idea of sets, the concept of multiset was introduced in [10] as a generalization of set wherein objects repeat in a collection. Multiset is very promising in mathematics, computer science, website design, etc. See [14, 15] for details. Since algebraic structures like groupoids, semigroups, monoids and groups were built from the idea of sets, it is then natural to introduce the algebraic notions of multiset. In [12], the term multigroup was proposed as a generalization of group in analogous to some non-classical groups such as fuzzy groups [13], intuitionistic fuzzy groups [3], etc. Although the term multigroup was earlier used in [4, 11] as an extension of group theory, it is only the idea of multigroup in [12] that captures multiset and relates to other non-classical groups. In fact, every multigroup is a multiset but the converse is not necessarily true and the concept of classical groups is a specialize multigroup with a unit count [5]. In furtherance of the study of multigroups, some properties of multigroups and the anal- ogous of isomorphism theorems were presented in [2]. Subsequently, in [1], the idea of order of an element with respect to multigroup and some of its related properties were discussed. A complete account on the concept of multigroups from different algebraic perspectives was outlined in [8]. The notions of upper and lower cuts of multigroups were proposed and some of 1Received April 26, 2017, Accepted November 2, 2017. 2 P.A. Ejegwa and A.M. Ibrahim their algebraic properties were explicated in [5]. In continuation to the study of homomorphism in multigroup setting (cf. [2, 12]), some homomorphic properties of multigroups were explored in [6]. In [9], the notion of multigroup actions on multiset was proposed and some results were established. An extensive work on normal submultigroups and comultisets of a multigroup were presented in [7]. In this paper, we explicate the notion of direct product of multigroups and its generaliza- tion. Some homomorphic properties of direct product of multigroups are also presented. This paper is organized as follows; in Section 2, some preliminary definitions and results are pre- sented to be used in the sequel. Section 3 introduces the concept of direct product between two multigroups and Section 4 considers the case of direct product of kth multigroups. Meanwhile, Section 5 contains some homomorphic properties of direct product of multigroups. §2. Preliminaries Definition 2.1([14]) Let X = x , x , , x , be a set. A multiset A over X is a cardinal- { 1 2 · · · n ···} valued function, that is, C : X N such that for x Dom(A) implies A(x) is a cardinal A → ∈ and A(x) = CA(x) > 0, where CA(x) denoted the number of times an object x occur in A. Whenever C (x)=0, implies x / Dom(A). A ∈ The set of all multisets over X is denoted by MS(X). Definition 2.2([15]) Let A, B MS(X), A is called a submultiset of B written as A B if ∈ ⊆ C (x) C (x) for x X. Also, if A B and A = B, then A is called a proper submultiset A ≤ B ∀ ∈ ⊆ 6 of B and denoted as A B. A multiset is called the parent in relation to its submultiset. ⊂ Definition 2.3([12]) Let X be a group. A multiset G is called a multigroup of X if it satisfies the following conditions: (i) C (xy) C (x) C (y) x, y X; G ≥ G ∧ G ∀ ∈ 1 (ii) C (x− )= C (x) x X, G G ∀ ∈ where C denotes count function of G from X into a natural number N and denotes minimum, G ∧ respectively. By implication, a multiset G is called a multigroup of a group X if 1 C (xy− ) C (x) C (y), x, y X. G ≥ G ∧ G ∀ ∈ It follows immediately from the definition that, C (e) C (x), x X, G ≥ G ∀ ∈ where e is the identity element of X. The count of an element in G is the number of occurrence of the element in G. While the Direct Product of Multigroups and Its Generalization 3 order of G is the sum of the count of each of the elements in G, and is given by n G = C (x ), x X.