فهرست مطالب

Journal of Mathematical Extension
Volume:16 Issue: 12, Apr 2022

  • تاریخ انتشار: 1401/07/24
  • تعداد عناوین: 10
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  • Maryam Rabii, Monireh Akbari Page 1

    We consider the real polynomials of degree d + 1 with a fixed point of multiplicity d ≥ 2. Such polynomials are conjugate to fa,d(x) = axd(x − 1) + x, a ∈ R \ {0}. In this family, the point 0 is always a non-hyperbolic fixed point. We prove that for given d, d′, and a, where d and d′ are positive even numbers and a belongs to a special subset of R−, there is a′ < 0 such that fa,d is topologically conjugate to fa′ ,d′ . Then we extend the properties that we have studied in case d = 2 to this family for every even d > 2.

    Keywords: l-Modal map, non-hyperbolic fixed point, order preserving bijection, topological conjugacy
  • Mohsen Shah Hosseini, Baharak Moosavi Page 2

    In this paper, we introduce some numerical radius inequalities for products of two Hilbert space operators. Some of our inequalities improve well-known ones.

    Keywords: Bounded linear operator, Hilbert space, norm inequality, numerical radius
  • Gholam Hossein Arab, Megerdich Toomanian Page 3

    It is widely known that the fundamental group of a Lie group, and in general a symmetric space, is abelian. In the current paper it is demonstrated that any finitely generated abelian group is the fundamental group of a compact Lie group. In addition, it is proved that for any arbitrary group there is a differentiable manifold of dimension greater than 3 whose fundamental group is that arbitrary group.

    Keywords: Lie groups, Fundamental group, Finitely generated abelian groups, Homotopy groups, Sectional curvature
  • Mehdi Nadjafikhah, Yadollah AryaNejad, Nishteman Zandi Page 4

    We study conformal geometry on two essential classes of pp-wave spaces‎, ‎i‎.e., ‎Cahen-Wallach and two-symmetric spaces‎. ‎This study leads to‎ ‎the general description of conformally Einstein metrics on the spaces under consideration‎. ‎Having settled a model for the potential energy of the capacitor‎, ‎we prove that the‎ ‎multiplying functions of conformal Einstein pp-wave spaces are solutions to the Schrodinger equation‎.

    Keywords: Conformal Einstein equation‎, ‎Schr, odinger equation‎, ‎Lorentzian two-symmetric space‎, ‎Quantum solutions
  • Mostafa Khorramizadeh Page 5

    In 2005 Avella and Vasil'Ev \cite{vas} presented an efficient cutting plane algorithm for solving an integer binary programming formulation of the university course timetabling problem (UCTP). Here, we present a new and efficient adjustment of the branch and price algorithm for solving the same formulation of UCTP. In every iteration of the branch and price algorithm, the column generation algorithm is used for solving the linear programming relaxation. For the first time, in this paper the set packing constraints of the UCTP formulation are chosen as the specially structured constraints of the column generation algorithm. Then, a new efficient two phase heuristic method is presented for solving the set packing problem. The resulting adjusted column generation is used within a branch and price algorithm and a comparison is performed with the cutting plane algorithm presented by Avella and Vasil'Ev.

    Keywords: University Course Timetabling, Branch, price, Column generation, Heuristic, Set packing
  • _ Sh. RezapourSh. Dehghani Page 6

    Abstract. By using discrete fractional calculus, we investigate the existence of solutions for a self-adjoint nite Nabla fractional di erence equation on the time scale Nb a+1 via initial boundary conditions. Also, we check some conditions for uniqueness of solution of the problem. For nding the solution, we use the Green function which de ned by using the Cauchy function. The principle of contraction mapping also plays an essential role in the existence of the solution. We provided two examples, a gure and numerical results to illustrate our main result. AMS Subject Classi cation: 34A12; 65L12. 

    Keywords: Self-adjoint, Nabla dierence operator, Dif- ference equation, time scale
  • khadijeh Ahmadi Amoli, Anna Hosseini, Saadat Ollah Faramarzi Abstract Page 7

    Let R be a commutative Noetherian ring, M be a finitely generated R-module and a be an ideal of R. For an arbitrary integer k ≥ −1, we introduce the concept of k-projective dimension of M de- noted by k-pdR M . We show that the finite k-projective dimension of M is at least k-depth(a, R) − k -depth(a, M ). As a generalization of the Intersection Theorem, we show that for any finitely generated R-module N , in certain conditions, k-pdR M is nearer upper bound for dimN than pdR M . Finally, if M is k-perfect, dimN ≤ k -gradeM that generalizes the Strong Intersection Theorem.

    Keywords: k-projective dimension, k-regular sequences, local cohomology modules, the Auslander-Buchsbaum Formula, the Intersection Theorem
  • Zahra Parvizi, Somayeh Motamed, Farhad Khaksar Haghani Page 8

    In this paper, the researchers defined the notions of normal, prime and nodal UP-filters in UP-algebras and investigated several properties of them. Also, the researchers state and proved some theorems in order to determine the relationships between this notions and some types of UP-filters in a UP-algebra and by some examples the researchers show that these notions are different.

    Keywords: UP-algebra, Nodal UP-filter, Normal UP-filter, Prime UP-filter
  • Mahdi Anbarloei Page 9

    The notion of multiplicative hyperrings is an important class of algebraic hyperstructures which generalize rings where the multiplication is a hyperoperation, while the addition is an operation ‎. ‎Let $R$ be a commutative multiplicative hyperring and ‎$‎\alpha \in End(R)‎$‎‎. ‎A proper hyperideal $I$ of $R$ is called ‎$‎\alpha‎$‎-prime if $x \circ y \subseteq I$ for some $x‎, ‎y \in R$ then $x \in I$ or $\alpha(y) \in I$‎. ‎Indeed‎, ‎the $\alpha‎$‎-prime hyperideals are a new generalization of prime hyperideals‎. ‎In this paper‎, ‎we aim to study ‎$‎\alpha‎$‎-prime hyperideals and give the basic properties of this new type of hyperideals‎.

  • Hanieh Golmakani, Abbas Jafarzadeh Page 10

    In this paper‎, ‎we generalize the concepts of ‎the‎ relative commutativity degree d(G,N) of a subgroup ‎N‎ ‎of a‎ ‎finite ‎group ‎‎‎G ‎and ‎also ‎the ‎tensor ‎degree ‎of a‎ ‎finite group. ‎We‎ introduce the relative n-tensor nilpotent degree of a finite group G ‎with ‎respect‎ to a subgroup $H$ of G ‎and ‎investigate ‎some ‎‎bounds ‎on ‎which.‎‎‎

    Keywords: Relative Tensor Degree, ‎Commutativity Degree, ‎Tensor ‎Degree