Displaying similar documents to “The superfocal subgroup”

On TI-subgroups and QTI-subgroups of finite groups

Ruifang Chen, Xianhe Zhao (2020)

Czechoslovak Mathematical Journal

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Let be a group. A subgroup of is called a TI-subgroup if or for every and is called a QTI-subgroup if for any . In this paper, a finite group in which every nonabelian maximal is a TI-subgroup (QTI-subgroup) is characterized.

On the existence of normal Sylow p-complements

Anna Luisa Gilotti, Luigi Serena (1980)

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

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Nella Nota gli autori danno una nuova condizione necessaria e sufficiente per l’esistenza di p-complementi di Sylow normali nei gruppi finiti.

On quotients of the space of orderings of the field ℚ(x)

Paweł Gładki, Bill Jacob (2016)

Banach Center Publications

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In this paper we present a method of obtaining new examples of spaces of orderings by considering quotient structures of the space of orderings - it is, in general, nontrivial to determine whether, for a subgroup the derived quotient structure is a space of orderings, and we provide some insights into this problem. In particular, we show that if a quotient structure arising from a subgroup of index 2 is a space of orderings, then it necessarily is a profinite one.

Finite groups with some SS-supplemented subgroups

Mengling Jiang, Jianjun Liu (2021)

Czechoslovak Mathematical Journal

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A subgroup of a finite group is said to be SS-supplemented in if there exists a subgroup of such that and is S-quasinormal in . We analyze how certain properties of SS-supplemented subgroups influence the structure of finite groups. Our results improve and generalize several recent results.

Finite -nilpotent groups with some subgroups weakly -supplemented

Liushuan Dong (2020)

Czechoslovak Mathematical Journal

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Suppose that is a finite group and is a subgroup of . Subgroup is said to be weakly -supplemented in if there exists a subgroup of such that (1) , and (2) if is a maximal subgroup of , then , where is the largest normal subgroup of contained in . We fix in every noncyclic Sylow subgroup of a subgroup satisfying and study the -nilpotency of under the assumption that every subgroup of with is weakly -supplemented in . Some recent results are generalized. ...

Every -group with all subgroups normal-by-finite is locally finite

Enrico Jabara (2018)

Czechoslovak Mathematical Journal

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A group has all of its subgroups normal-by-finite if is finite for all subgroups of . The Tarski-groups provide examples of -groups ( a “large” prime) of nonlocally finite groups in which every subgroup is normal-by-finite. The aim of this paper is to prove that a -group with every subgroup normal-by-finite is locally finite. We also prove that if for every subgroup of , then contains an Abelian subgroup of index at most .

On solvability of finite groups with some -supplemented subgroups

Jiakuan Lu, Yanyan Qiu (2015)

Czechoslovak Mathematical Journal

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A subgroup of a finite group is said to be -supplemented in if there exists a subgroup of such that and is -permutable in . In this paper, we first give an example to show that the conjecture in A. A. Heliel’s paper (2014) has negative solutions. Next, we prove that a finite group is solvable if every subgroup of odd prime order of is -supplemented in , and that is solvable if and only if every Sylow subgroup of odd order of is -supplemented in . These results...

On weakly-supplemented subgroups of finite groups

Qingjun Kong (2019)

Czechoslovak Mathematical Journal

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A subgroup of a finite group is weakly-supplemented in if there exists a proper subgroup of such that . In this paper, some interesting results with weakly-supplemented minimal subgroups to a smaller subgroup of are obtained.

A note on weakly-supplemented subgroups of finite groups

Hong Pan (2018)

Czechoslovak Mathematical Journal

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A subgroup of a finite group is weakly-supplemented in if there exists a proper subgroup of such that . In the paper, we extend one main result of Kong and Liu (2014).

A note on weakly-supplemented subgroups and the solvability of finite groups

Xin Liang, Baiyan Xu (2022)

Czechoslovak Mathematical Journal

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Suppose that is a finite group and is a subgroup of . The subgroup is said to be weakly-supplemented in if there exists a proper subgroup of such that . In this note, by using the weakly-supplemented subgroups, we point out several mistakes in the proof of Theorem 1.2 of Q. Zhou (2019) and give a counterexample.

On locally S-closed spaces

Takashi Noiri (1983)

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

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Si studiano le condizioni sotto cui l’immagine (o l'immagine inversa) di uno spazio localmente S-chiuso sia localmente S-chiuso.

On -conjugate-permutability of Sylow subgroups

Xianhe Zhao, Ruifang Chen (2016)

Czechoslovak Mathematical Journal

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A subgroup of a finite group is said to be conjugate-permutable if for all . More generaly, if we limit the element to a subgroup of , then we say that the subgroup is -conjugate-permutable. By means of the -conjugate-permutable subgroups, we investigate the relationship between the nilpotence of and the -conjugate-permutability of the Sylow subgroups of and under the condition that , where and are subgroups of . Some results known in the literature are improved...

\bf{L}-embedding, Amalgamation and \bf{L}-elementary equivalence

Daniele Mundici (1982)

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

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Ogni logica L genera canonicamente la L-equivalenza \equiv_{L}e la L-immersione \underset{L}{\rightarrow} proprio come la logica del primo ordine genera l’equivalenza elementare \equiv e l’immersione elementare \lesssim. Astraendo da L, è interessante studiare in sè relazioni d’equivalenza e di immersione generali tra strutture. Mostriamo che esiste una corrispondenza biunivoca tra relazioni d’equivalenza con la proprietà di Robinson e relazioni d’immersione con la proprietà di Amalgamazione Forte (AP^{+}). Caratterizziamo algebricamente...

On the existence of scrolls in \bf{P}^{4}

Antonio Lanteri (1980)

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

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Si dimostra il seguente risultato. Sia X una superficie proiettivamente rigata, non iperpiana, di \bf{P}^{4}; allora X è la rigata cubica oppure è una rigata quintica ellittica. Si descrive inoltre una nuova generazione proiettiva delle rigate quintiche ellittiche di \bf{P}^{4}.

Cylindrical real hyper surfaces in \mathbf{C}^{n}

Claudio Rea (1981)

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

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Si stabiliscono due condizioni sufficienti per un germe di ipersuperficie reale di classe c^{\infty} in \mathbf{C}^{n} affinchè esistano coordinate olomorfe rispetto alle quali l'ipersuperficie risulti essere il luogo di zeri di una funzione di k<n variabili e k sia minimale rispetto a questa proprietà. In altre parole si vuole che l'ipersuperficie, a meno di una trasformazione bi-olomorfa, sia l’unione di sottovarietà lineari complesse, parallele di dimensione n—k.