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On the nontrivial solvability of systems of homogeneous linear equations over in ZFC

Jan Šaroch (2020)

Commentationes Mathematicae Universitatis Carolinae

Motivated by the paper by H. Herrlich, E. Tachtsis (2017) we investigate in ZFC the following compactness question: for which uncountable cardinals κ , an arbitrary nonempty system S of homogeneous -linear equations is nontrivially solvable in provided that each of its subsystems of cardinality less than κ is nontrivially solvable in ?

On the number of abelian groups of a given order (supplement)

Hong-Quan Liu (1993)

Acta Arithmetica

1. Introduction. The aim of this paper is to supply a still better result for the problem considered in [2]. Let A(x) denote the number of distinct abelian groups (up to isomorphism) of orders not exceeding x. We shall prove Theorem 1. For any ε > 0, A ( x ) = C x + C x 1 / 2 + C x 1 / 3 + O ( x 50 / 199 + ε ) , where C₁, C₂ and C₃ are constants given on page 261 of [2]. Note that 50/199=0.25125..., thus improving our previous exponent 40/159=0.25157... obtained in [2]. To prove Theorem 1, we shall proceed along the line of approach presented in [2]....

On the number of isomorphism classes of derived subgroups

Leyli Jafari Taghvasani, Soran Marzang, Mohammad Zarrin (2019)

Czechoslovak Mathematical Journal

We show that a finite nonabelian characteristically simple group G satisfies n = | π ( G ) | + 2 if and only if G A 5 , where n is the number of isomorphism classes of derived subgroups of G and π ( G ) is the set of prime divisors of the group G . Also, we give a negative answer to a question raised in M. Zarrin (2014).

On the number of solutions of equation x p k = 1 in a finite group

Yakov Berkovich (1995)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Theorem A yields the condition under which the number of solutions of equation x p k = 1 in a finite p -group is divisible by p n + k (here n is a fixed positive integer). Theorem B which is due to Avinoam Mann generalizes the counting part of the Sylow Theorem. We show in Theorems C and D that congruences for the number of cyclic subgroups of order p k which are true for abelian groups hold for more general finite groups (for example for groups with abelian Sylow p -subgroups).

On the number of subgroups of finite abelian groups

Aleksandar Ivić (1997)

Journal de théorie des nombres de Bordeaux

Let T ( x ) = K 1 x log 2 x + K 2 x log x + K 3 x + Δ ( x ) , where T ( x ) denotes the number of subgroups of all abelian groups whose order does not exceed x and whose rank does not exceed 2 , and Δ ( x ) is the error term. It is proved that 1 X Δ 2 ( x ) d x X 2 log 31 / 3 X , 1 X Δ 2 ( x ) d x = Ω ( X 2 log 4 X ) .

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