1,720,974 research outputs found

    A new characteristic subgroup for pushing up I

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    Let T be a finite p-group. In this paper we introduce a new characteristic subgroup W(T) of T containing Z(T). This subgroup allows to give the structure of p-minimal finite groups G of characteristic p with PSL2(pn)-factor group which satisfy Z(T) G and W(T) G. This result generalizes a classical pushing up result obtained by Baumann [1] (for p = 2) and Niles [8]

    p-Groups of Small Breadth

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    In this paper we give a characterization of p-groups of breadth 2 for all primes and of breadth 3 for p odd

    Baumann-components of finite groups of characteristic p, reduction theorems

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    We continue the project started in "Baumann-components of finite groups of characteristic p, general theory" to describe the structure of the finite groups G of characteristic p in terms of their Baumann components and the conjugacy class Baup(G). The reduction theorem proved in that paper allows to assume that G has a unique Baumann component. In this paper we use this property to determine the isomorphism type of G/Op(G) and the action of G on Ω1(Z(Op(G))). In addition, we prove reduction theorems which allow to focus on groups G which satisfy G/Op(G)≅SLn(q), Sp2n(q) or G2(q) and Op(G)⩽B for B∈Baup(G)

    Baumann-components of finite groups of characteristic p, the W(B)-theorem

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    This paper completes the investigation of finite CK-groups of characteristic p in terms of their Baumann components we began in [Baumann-components of finite groups in characteristic p, general theory] and [Baumann-components of finite groups in characteristic p, reduction theorems]. In this paper we define for each finite p-group B a non-trivial characteristic subgroup W(B) and for each finite CK-group G of characteristic p with B in Baup(G), subnormal subgroups of G called Baumann blocks of G. We prove that G = N_G(W(B))E_W(G), where E_W(G) is the normal subgroup generated by the Baumann blocks of G. Moreover, we give the exact structure of the Baumann blocks of G and show that any two distinct Baumann blocks centralize each other

    Baumann-components of finite groups of characteristic p, general theory

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    In this paper we introduce a new conjugacy class Bau_p(G) of p-subgroups of finite groups G of characteristic p. We then prove some factorization and decomposition theorems related to this conjugacy class. In particular, these results show that the only obstructions for B∈Bau_p(G) being normal in G are the Baumann components of G, a class of subnormal subgroups E with E/Op(E) quasisimple or SL2(p)′ for p≤3

    The P!-Theorem

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    In this paper we prove a result that is used in the investigation of finite K_p-groups of local characteristic p. More precisely, we show that one of the cases given in the "Structure Theorem" by Meierfrankenfeld, Stellmacher and Stroth does not occur

    The tildePtilde P!-theorem

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    In this paper we prove a result that is used in the investigation of finite K_p-groups of local characteristic p. It is part of an attempt to revise a major part of the classification of the finite simple groups. A description of this program can be found in [U.Meierfrankenfeld, B.Stellmacher, G.Stroth, "Finite groups of local characteristic p: an overview", Groups, Combinatorics and Geometry, Durham, 2001 (World Scientific Publishing, River Edge, NJ, 2003) pp. 155-192]

    The P~!\widetilde P!-Theorem

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    The paper under review is part of an ongoing project to give a proof for large parts of the classification of the finite simple groups which is different from the existing one. Moreover, the authors prove some result which is of independent interest.\par They consider the usual amalgam set up, i.e., two groups M1,M2M_1,M_2 which are of characteristic pp-type, share a common Sylow pp-subgroup but no nontrivial normal subgroup of M1,M2\langle M_1,M_2\rangle. Now the special assumptions are (i) Z(Mi)=1Z(M_i)=1, i=1,2i= 1,2, (ii) There is YMiMiY_{M_i}\triangleleft M_i with Mi/CMi(Yi)SL3(qi)M_i/C_{M_i}(Y_i)\cong\text{SL}_3(q_i), Sp4(qi)\text{Sp}_4(q_i), qi=pniq_i=p^{n_i}, or Sp4(2)\text{Sp}_4(2)' (qi=p=2q_i=p=2) and [YMi,Op(Mi)][Y_{M_i},O^p(M_i)] is the natural module, i=1,2i=1,2. (iii) CMi(Yi)=Op(Mi)C_{M_i}(Y_i)=O_p(M_i) or qi=2q_i=2 and Mi/O2(Mi)3Sp4(2)M_i/O_2(M_i)\cong 3\text{Sp}4(2) or 3Sp4(2)3\text{Sp}_4(2)'; (iv) There is a 2-dimensional singular subspace WW in [YMi,Op(Mi)][Y_{M_i},O^p(M_i)] such that Op(NMi(W))M1M2O^{p'}(N_{M_i}(W))\le M_1\cap M_2, i=1,2i= 1,2.\par Then the authors show that this setup does just occur in very special situations. Either p=2p=2, O2(Mi)=YMiO_2(M_i)=Y_{M_i} and Mi/O2(Mi)Sp4(2)M_i/O_2(M_i)\cong\text{Sp}_4(2)' or Sp4(2)\text{Sp}_4(2), YMi=24|Y_{M_i}|=2^4 or 252^5 or q=q1=q2q=q_1=q_2, p=3p=3 or q=5q=5 and Mi/Op(Mi)SL3(q)M_i/O_p(M_i)\cong\text{SL}_3(q), and Op(Mi)/YMiO_p(M_i)/Y_{M_i} and YMiY_{M_i} are natural SL3(q)\text{SL}_3(q)-modules dual to each other.\par This result is similar to the result due to {\it B. Stellmacher} and {\it F. G. Timmesfeld} [Mem. Am. Math. Soc. 649 (1998; Zbl 0911.20024)] but does not follow from that result. This is now used to get a technical result, the P~\widetilde P-theorem. This under certain assumptions, which are technical, says basically the following. Let GG be a group with Op(G)=1O_p(G)=1, SSylp(G)S\in\text{Syl}_p(G), of local characteristic pp, and C~\widetilde C be a maximal pp-local containing NH(Ω1(Z(S)))N_H(\Omega_1(Z(S))). As the generic simple group of local characteristic pp is a group of Lie type over a field of characteristic pp, the aim is to get a geometry for GG. In this sense then C~\widetilde C is a maximal parabolic. Now, the authors consider a minimal parabolic PC~P\nleq\widetilde C. Under a further technical assumption, they show that there is a unique minimal parabolic P~\widetilde P containing SS, which does not normalize PP or there is one of the exceptions described by the theorem above. Further, they show that the group generated by PP and P~\widetilde P is a rank 2 Lie group. So if C~\widetilde C induces a Lie group this result provides us with a building geometry for P,C~\langle P,\widetilde C\rangle. [Gernot Stroth (Halle)

    General offender theory

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    We present an offender theory that is symmetric in offender and offended group and also a replacement theorem that does not need that the groups in question are abelian. We then use this theory to define variations of Thompson and Baumann subgroups and prove a general Baumann argument. (C) 2017 Elsevier Inc. All rights reserved

    Transitive permutation groups with cyclic point stabilizers of maximum order

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    The purpose of this paper is to classify transitive permutation groups where the stabiliser is cyclic of order n1n-1 where the degree is n1n-1. This is a continuation of a paper by {\it A. Lucchini} [Atti Accad. Naz. Lincei, Cl. Sci. Fis. Mat. Nat., IX. Ser., Rend. Lincei, Mat. Appl. 9, No. 4, 241-243 (1998; Zbl 0940.20006)]. However the main result is more general, Theorem: Let GG be a finite group and let π\pi be a set of primes dividing the order of GG. Assume that GG has an Abelian Hall π\pi-subgroup, QQ. Then one of the following hold: (a) Oπ(G)1O_\pi(G)\neq 1, (b) G>2Q2|G|>2|Q|^2, or (c) G=E1××ErG=E_1\times\cdots\times E_r where each EiE_i is a 22-transitive Frobenius group whose complement is a π\pi-group.\par The question arose from a paper by {\it L. Babai}, {\it A. J. Goodman} and {\it L. Pyber} [J. Algebra 195, No. 1, 1-29 (1997; Zbl 0886.20020)]. [Alan R. Camina (Norwich)
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