• Title/Summary/Keyword: prime graph

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THE TOTAL GRAPH OF A COMMUTATIVE RING WITH RESPECT TO PROPER IDEALS

  • Abbasi, Ahmad;Habibi, Shokoofe
    • Journal of the Korean Mathematical Society
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    • v.49 no.1
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    • pp.85-98
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    • 2012
  • Let R be a commutative ring and I its proper ideal, let S(I) be the set of all elements of R that are not prime to I. Here we introduce and study the total graph of a commutative ring R with respect to proper ideal I, denoted by T(${\Gamma}_I(R)$). It is the (undirected) graph with all elements of R as vertices, and for distinct x, y ${\in}$ R, the vertices x and y are adjacent if and only if x + y ${\in}$ S(I). The total graph of a commutative ring, that denoted by T(${\Gamma}(R)$), is the graph where the vertices are all elements of R and where there is an undirected edge between two distinct vertices x and y if and only if x + y ${\in}$ Z(R) which is due to Anderson and Badawi [2]. In the case I = {0}, $T({\Gamma}_I(R))=T({\Gamma}(R))$; this is an important result on the definition.

THE ZERO-DIVISOR GRAPH UNDER GROUP ACTIONS IN A NONCOMMUTATIVE RING

  • Han, Jun-Cheol
    • Journal of the Korean Mathematical Society
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    • v.45 no.6
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    • pp.1647-1659
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    • 2008
  • Let R be a ring with identity, X the set of all nonzero, nonunits of R and G the group of all units of R. First, we investigate some connected conditions of the zero-divisor graph $\Gamma(R)$ of a noncommutative ring R as follows: (1) if $\Gamma(R)$ has no sources and no sinks, then $\Gamma(R)$ is connected and diameter of $\Gamma(R)$, denoted by diam($\Gamma(R)$) (resp. girth of $\Gamma(R)$, denoted by g($\Gamma(R)$)) is equal to or less than 3; (2) if X is a union of finite number of orbits under the left (resp. right) regular action on X by G, then $\Gamma(R)$ is connected and diam($\Gamma(R)$) (resp. g($\Gamma(R)$)) is equal to or less than 3, in addition, if R is local, then there is a vertex of $\Gamma(R)$ which is adjacent to every other vertices in $\Gamma(R)$; (3) if R is unit-regular, then $\Gamma(R)$ is connected and diam($\Gamma(R)$) (resp. g($\Gamma(R)$)) is equal to or less than 3. Next, we investigate the graph automorphisms group of $\Gamma(Mat_2(\mathbb{Z}_p))$ where $Mat_2(\mathbb{Z}_p)$ is the ring of 2 by 2 matrices over the galois field $\mathbb{Z}_p$ (p is any prime).

A GENERALIZED IDEAL BASED-ZERO DIVISOR GRAPHS OF NEAR-RINGS

  • Dheena, Patchirajulu;Elavarasan, Balasubramanian
    • Communications of the Korean Mathematical Society
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    • v.24 no.2
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    • pp.161-169
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    • 2009
  • In this paper, we introduce the generalized ideal-based zero-divisor graph structure of near-ring N, denoted by $\widehat{{\Gamma}_I(N)}$. It is shown that if I is a completely reflexive ideal of N, then every two vertices in $\widehat{{\Gamma}_I(N)}$ are connected by a path of length at most 3, and if $\widehat{{\Gamma}_I(N)}$ contains a cycle, then the core K of $\widehat{{\Gamma}_I(N)}$ is a union of triangles and rectangles. We have shown that if $\widehat{{\Gamma}_I(N)}$ is a bipartite graph for a completely semiprime ideal I of N, then N has two prime ideals whose intersection is I.

Disproof of Hadwiger Conjecture (Hadwiger 추측의 반증)

  • Lee, Sang-Un
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.14 no.5
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    • pp.263-269
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    • 2014
  • In this paper, I disprove Hadwiger conjecture of the vertex coloring problem, which asserts that "All $K_k$-minor free graphs can be colored with k-1 number of colors, i.e., ${\chi}(G)=k$ given $K_k$-minor." Pursuant to Hadwiger conjecture, one shall obtain an NP-complete k-minor to determine ${\chi}(G)=k$, and solve another NP-complete vertex coloring problem as a means to color vertices. In order to disprove Hadwiger conjecture in this paper, I propose an algorithm of linear time complexity O(V) that yields the exact solution to the vertex coloring problem. The proposed algorithm assigns vertex with the minimum degree to the Maximum Independent Set (MIS) and repeats this process on a simplified graph derived by deleting adjacent edges to the MIS vertex so as to finally obtain an MIS with a single color. Next, it repeats the process on a simplified graph derived by deleting edges of the MIS vertex to obtain an MIS whose number of vertex color corresponds to ${\chi}(G)=k$. Also presented in this paper using the proposed algorithm is an additional algorithm that searches solution of ${\chi}^{{\prime}{\prime}}(G)$, the total chromatic number, which also remains NP-complete. When applied to a $K_4$-minor graph, the proposed algorithm has obtained ${\chi}(G)=3$ instead of ${\chi}(G)=4$, proving that the Hadwiger conjecture is not universally applicable to all the graphs. The proposed algorithm, however, is a simple algorithm that directly obtains an independent set minor of ${\chi}(G)=k$ to assign an equal color to the vertices of each independent set without having to determine minors in the first place.

ON FINITE GROUPS WITH THE SAME ORDER TYPE AS SIMPLE GROUPS F4(q) WITH q EVEN

  • Daneshkhah, Ashraf;Moameri, Fatemeh;Mosaed, Hosein Parvizi
    • Bulletin of the Korean Mathematical Society
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    • v.58 no.4
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    • pp.1031-1038
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    • 2021
  • The main aim of this article is to study quantitative structure of finite simple exceptional groups F4(2n) with n > 1. Here, we prove that the finite simple exceptional groups F4(2n), where 24n + 1 is a prime number with n > 1 a power of 2, can be uniquely determined by their orders and the set of the number of elements with the same order. In conclusion, we give a positive answer to J. G. Thompson's problem for finite simple exceptional groups F4(2n).

CUBIC s-REGULAR GRAPHS OF ORDER 12p, 36p, 44p, 52p, 66p, 68p AND 76p

  • Oh, Ju-Mok
    • Journal of applied mathematics & informatics
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    • v.31 no.5_6
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    • pp.651-659
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    • 2013
  • A graph is $s$-regular if its automorphism group acts regularly on the set of its $s$-arcs. In this paper, the cubic $s$-regular graphs of order 12p, 36p, 44p, 52p, 66p, 68p and 76p are classified for each $s{\geq}1$ and each prime $p$. The number of cubic $s$-regular graphs of order 12p, 36p, 44p, 52p, 66p, 68p and 76p is 4, 3, 7, 8, 1, 4 and 1, respectively. As a partial result, we determine all cubic $s$-regular graphs of order 70p except for $p$ = 31, 41.

ON THE NUMBER OF SEMISTAR OPERATIONS OF SOME CLASSES OF PRUFER DOMAINS

  • Mimouni, Abdeslam
    • Bulletin of the Korean Mathematical Society
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    • v.56 no.6
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    • pp.1485-1495
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    • 2019
  • The purpose of this paper is to compute the number of semistar operations of certain classes of finite dimensional $Pr{\ddot{u}}fer$ domains. We prove that ${\mid}SStar(R){\mid}={\mid}Star(R){\mid}+{\mid}Spec(R){\mid}+ {\mid}Idem(R){\mid}$ where Idem(R) is the set of all nonzero idempotent prime ideals of R if and only if R is a $Pr{\ddot{u}}fer$ domain with Y -graph spectrum, that is, R is a $Pr{\ddot{u}}fer$ domain with exactly two maximal ideals M and N and $Spec(R)=\{(0){\varsubsetneq}P_1{\varsubsetneq}{\cdots}{\varsubsetneq}P_{n-1}{\varsubsetneq}M,N{\mid}P_{n-1}{\varsubsetneq}N\}$. We also characterize non-local $Pr{\ddot{u}}fer$ domains R such that ${\mid}SStar(R){\mid}=7$, respectively ${\mid}SStar(R){\mid}=14$.

ON STRONGLY QUASI PRIMARY IDEALS

  • Koc, Suat;Tekir, Unsal;Ulucak, Gulsen
    • Bulletin of the Korean Mathematical Society
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    • v.56 no.3
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    • pp.729-743
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    • 2019
  • In this paper, we introduce strongly quasi primary ideals which is an intermediate class of primary ideals and quasi primary ideals. Let R be a commutative ring with nonzero identity and Q a proper ideal of R. Then Q is called strongly quasi primary if $ab{\in}Q$ for $a,b{\in}R$ implies either $a^2{\in}Q$ or $b^n{\in}Q$ ($a^n{\in}Q$ or $b^2{\in}Q$) for some $n{\in}{\mathbb{N}}$. We give many properties of strongly quasi primary ideals and investigate the relations between strongly quasi primary ideals and other classical ideals such as primary, 2-prime and quasi primary ideals. Among other results, we give a characterization of divided rings in terms of strongly quasi primary ideals. Also, we construct a subgraph of ideal based zero divisor graph ${\Gamma}_I(R)$ and denote it by ${\Gamma}^*_I(R)$, where I is an ideal of R. We investigate the relations between ${\Gamma}^*_I(R)$ and ${\Gamma}_I(R)$. Further, we use strongly quasi primary ideals and ${\Gamma}^*_I(R)$ to characterize von Neumann regular rings.

A New Digital Image Steganography Approach Based on The Galois Field GF(pm) Using Graph and Automata

  • Nguyen, Huy Truong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.9
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    • pp.4788-4813
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    • 2019
  • In this paper, we introduce concepts of optimal and near optimal secret data hiding schemes. We present a new digital image steganography approach based on the Galois field $GF(p^m)$ using graph and automata to design the data hiding scheme of the general form ($k,N,{\lfloor}{\log}_2p^{mn}{\rfloor}$) for binary, gray and palette images with the given assumptions, where k, m, n, N are positive integers and p is prime, show the sufficient conditions for the existence and prove the existence of some optimal and near optimal secret data hiding schemes. These results are derived from the concept of the maximal secret data ratio of embedded bits, the module approach and the fastest optimal parity assignment method proposed by Huy et al. in 2011 and 2013. An application of the schemes to the process of hiding a finite sequence of secret data in an image is also considered. Security analyses and experimental results confirm that our approach can create steganographic schemes which achieve high efficiency in embedding capacity, visual quality, speed as well as security, which are key properties of steganography.

ON THE 2-ABSORBING SUBMODULES AND ZERO-DIVISOR GRAPH OF EQUIVALENCE CLASSES OF ZERO DIVISORS

  • Shiroyeh Payrovi;Yasaman Sadatrasul
    • Communications of the Korean Mathematical Society
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    • v.38 no.1
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    • pp.39-46
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    • 2023
  • Let R be a commutative ring, M be a Noetherian R-module, and N a 2-absorbing submodule of M such that r(N :R M) = 𝖕 is a prime ideal of R. The main result of the paper states that if N = Q1 ∩ ⋯ ∩ Qn with r(Qi :R M) = 𝖕i, for i = 1, . . . , n, is a minimal primary decomposition of N, then the following statements are true. (i) 𝖕 = 𝖕k for some 1 ≤ k ≤ n. (ii) For each j = 1, . . . , n there exists mj ∈ M such that 𝖕j = (N :R mj). (iii) For each i, j = 1, . . . , n either 𝖕i ⊆ 𝖕j or 𝖕j ⊆ 𝖕i. Let ΓE(M) denote the zero-divisor graph of equivalence classes of zero divisors of M. It is shown that {Q1∩ ⋯ ∩Qn-1, Q1∩ ⋯ ∩Qn-2, . . . , Q1} is an independent subset of V (ΓE(M)), whenever the zero submodule of M is a 2-absorbing submodule and Q1 ∩ ⋯ ∩ Qn = 0 is its minimal primary decomposition. Furthermore, it is proved that ΓE(M)[(0 :R M)], the induced subgraph of ΓE(M) by (0 :R M), is complete.