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International Journal of Group Theory - Volume:10 Issue: 2, Jun 2021

International Journal of Group Theory
Volume:10 Issue: 2, Jun 2021

  • تاریخ انتشار: 1399/10/25
  • تعداد عناوین: 5
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  • Maghsoud Jahani, Yadollah Marefat *, Hasan Refaghat, Bahram Vakili Fasaghandisi Pages 55-60

    ‎Let $ G $ be a finite group and ( psi(G)=sum_{gin G}o(g) )‎, ‎where $ o(g) $ denotes the order of $gin G$‎. ‎We show that the Conjecture 4.6.5 posed in [Group Theory and Computation‎, ‎(2018) 59-90]‎, ‎is incorrect‎. ‎In fact‎, ‎we find a pair of finite groups $G$ and $S$ of the same order such that $ psi(G)<psi(S)$‎, ‎with $G$ solvable and $S$ simple‎.

    * The formulas are not displayed correctly.

    Keywords: ‎Finite group‎, ‎element orders sum‎, ‎solvable group‎, ‎simple group
  • William Cocke * Pages 61-64
    ‎In this note we prove an analog of Hilbert's theorem 90 for finite nilpotent groups‎. ‎Our version of Hilbert's theorem 90 was inspired by the Boston--Bush--Hajir (BBH) heuristics in number theory and will be useful in extending the BBH heuristics beyond quadratic field extensions‎.
    Keywords: ‎Nilpotent groups‎, ‎BBH Heuristics‎, ‎Hilbert's Theorem 90
  • Izabela Malinowska * Pages 65-74

    P‎. ‎Hall proved that a finite group $G$ is supersoluble with elementary abelian Sylow subgroups if and only if every subgroup of $G$ is complemented in $G$‎. ‎He called such groups complemented‎. ‎A‎. ‎Ballester-Bolinches and X‎. ‎Guo‎ ‎established the structure of minimal non-complemented groups‎. ‎We give the classification of finite non-soluble groups‎ ‎all of whose second maximal subgroups are complemented groups‎. ‎We also prove that every finite group with less than‎ ‎$21$ non-complemented non-minimal ${2,3,5}$-subgroups is soluble‎.


    * The formulas are not displayed correctly.

    Keywords: Complemented subgroups, Complemented groups, Minimal non-complemented groups, Finite groups
  • Derek J. S. Robinson * Pages 75-88

    ‎The effect of restricting the set of primes dividing the orders of the finite quotients of a group is investigated‎. ‎Particular attention is paid to abelian‎, ‎soluble‎, ‎locally soluble and locally finite groups‎. ‎The connection with the extraction of roots is explored‎.

    * The formulas are not displayed correctly.

    Keywords: ‎Finite quotients‎, ‎Prime divisors
  • Masoud Pourhasan, Hossein Doostie * Pages 89-95

    ‎For a given odd prime $p$‎, ‎we investigate the power graphs of three classes of finite groups‎: ‎the elementary abelian groups of exponent $p$‎, ‎and the extra special groups of exponents $p$ or $p^2$‎. ‎We show that these power graphs are Eulerian for every $p$‎. ‎As a corollary‎, ‎we describe two classes of non-isomorphic groups with isomorphic power graphs‎. ‎In addition‎, ‎we prove that the clique graphs of the power graphs of two considered classes are complete‎. 

    * The formulas are not displayed correctly.

    Keywords: ‎Power graphs‎, ‎non-group semigroups‎, ‎semidirect product