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有限群超可解的一些充分条件

2021-11-17 来源:小侦探旅游网
第33卷第1期 2018年2月 成都信息工程大学学报 V01.33 No.1 Feb.2018 JOURNAL OF CHENGDU UNIVERSITY OF INFORMATION TECHNOL0GY 文章编号:2096-1618(2018)0l-0099-04 Some Suficient Conditions for Supers0lVabilfity 0f a Finite Group YOU Ze,LI Bao-jun (College of Applied Mathematics,Chengdu University of Information Technology,Chengdu 6 1 0025,China) Abstract:Let X be a non—empty subset of G.A subgroup H of a finite group G is said to be X-s-semipermutable in G if H has a supplement T in G such that H is X-permutable with any Sylow subgroup of Tfor some ∈X.Let P be a sylowP— subgroup of a inifte group G.and d a powerof P such that l≤d<l P 1.We derive some theorems and corollaries that ex— tend known results concerning S—semipermutable subgroups.We obtained in this paper that if H n ov(G)is X-s—semiper— mutable in G for all normal subgroups H of G with『HI=d,where X is a soluble normal subgroup of G,then either G isP—su— persoluble or else l P n o (G)f>d. Keywords:fundamental mathematics;algebra;finite group;p—supersoluble; s-semipermutable;primary subgroups CLC number:O152.1 Document code:A doi:10.16836/j.cnki.icult.2018.01.017 0 Introduction All groups considered in this paper are finite.Nota- tions and terminologies are standard,and the reader is re— ferred to the texts of W.Guo【 ]and Hupert[2]for nota. tions and terminologies not introduced.A group G is said to be P-soluble if every chief factor is either a P 一group or a p-group,and G is said to be p-supersoluble if G is p-sol— uble and every its P—chief factor is of order P.The sub— G.A subgroup H of a finite group G is said tobe permuta- ble(or quasinorma1)in G if H permutes with any sub— group of G,and H is said to be S-permutable in G if H permutes with any Sylow subgroup of G.If日has a sup— plement T in G such that H permutes with all Sylow sub— group of T,then H is called S-semipermutanle in G.Ball· ester-Bolinches and eta1.generalized Theorem 1.1 in the paper[4j and proved the results. group O (G)of a group G is the subgroup generated by all P elements of G,which is also the minimal normal subgroup of G with the quotient is a P group.In the past, Theorem B([5,Theorem 2])LetP∈Sylp(G)and let d be a power of P such that 1≤d<I P I.Let U= O (G)and assume that H n op(G)is S-semipermutable in G for all subgroups日 Pwith IHI=d.Then either G is P-supersoluble,or else I P n uI>d. Let X be a subset of a group G and H,T be sub— groups of G.Then H is said to be X—permutable。。 with T in G if日 =r日for some ∈X.Clearly.a permutable subgroup of G is a subgroup that 1一permutes with all sub- group of G.And,if X=G,a subgroup which X-permutes with all subgroup of Gisc-permutable in G .X—permut- ability of subgroups is studied extensively and in L s Jthe .many researchers studied the influence of Oo(G)on the structure of G.For example,in L3 JGuo and Issacs ob- ,tained the following result: Theorem A([3,Theorem B])Let P∈Sylp(G) and d be a power ofP such that 1≤d<I P I.Let U= O (G)and assume that H n u<l u for all subgroups 日 P with I H I=d.Then either G is p-supersoluble.or else I尸n l>d. In the later researches,it is found that the normality of H in Theorem 1.1 in the paper[ can be weakened. following definition were proposed. Let A,B be subgroups of a group G.Then A is said to be permutable with B if AB=BA,that is,AB is a subgroup of Definition[8,definition 1]Let A be subgroup of a group G and X a non-empty subset of G.Then A is said to be X-s-semipermutable in G if A has a supplememt T in G such that A is X—permutable with all Sylow subgroups of T. Received date:2017-06-30 It is easy to find that a S-semipermutable subgroup is X·-s-·semipermutable subgroup in a group G for any sub·- Foundation item:Project Supported by the National Natural Science Foundation of China(1 1471055,1 1371335) 100 成都信息工程大学 学报 第33卷 group X of G,but an X—s—permutable subgroup is not nec— essarily to be S-permutable in G if is not 1.We derive 2 Proof of Theorem C Assume that the result is not true and let G be a some theorems and corollaries that extend known results concerning S-semipermutable subgroups[ 一 .To develop the work in[3 3in this paper,we obtained the following ,counterexample of least order.Write U=0p(G),K Pn U.Then I KI≤d and G is not P—supersoluble.In par— theorem. Theorem C Let G be a finite group and X a soluble ticular,K≠1 and d≥P.Write|U={H P l l H l=d} .normal subgroup of G.LetP be a prime.LetP∈Syl(G) pBy hypothesis. n U is X—s—semipermutable in G for with P be a prime and let d be a power of P such that 1≤ d<l PI.Write U= (G),and assume that Hn Op(G) is X-s—semipermutable in G for all subgroups日 P with IHf= .Then either G is p-supersoluble.or else fPn } . 1 Some Lemmas To prove Theorem,we list some known results as lemmas in this section. Lemma I.1[8,Lemma 2.1]Let A and X be sub. rgoups of G and N<3G.Then: (1)If H is a permutable subgroup of G,A is X semipermutable in G,then HA is a X—s—semipermutable subgroup of G. (2)If A is X.s.semipermutable in G and T∈ (A),then AN/N is XN/N-s—semipermutable in G/N and"v/Ⅳ∈(XN/N) (AN/N) (3)If A/N is XN/N—s—semipermutable in G/T and Ⅳ∈(XN/N) (A/N),then A is X—s-semipermutable in G and T∈X (A) (4)IfA is X—s—semipermutable in G,A≤D G and ≤D.then A is X—s—semipermutable in D (5)If T∈X (A)and A≤Nc(X),then r∈ (A),for any ∈G. (6)If A is X—s—semipermutable in G and X≤D, then A is D-·s—-semipermutable in G Lemma 1.2『16,Lemma 3.13]Let A and B be some subgroups of a group G such that G≠AB andAB = B A for each ∈G.Then G has a proper normal sub— group N such that eitherA≤NorB≤N. Lemma 1.3[16,Lemma 2.5]Let G be a group,P a p-subgroup of G and Q a q-subgroup of G,where P,q are different primes dividing l G 1.If L is a subnormal subgroup of G and PQ=QP,then PQ n =(P n L)(Q n L) each H∈tU. Step 1 0。 (G)=1 Write V=0 ,(G)and assume that V≠1.Consider the factor group G:G/V.LetHbe a normal subgroup of of order d.Then there is H∈|U such that曰=HWV. Since H n u is X-s-semipermutable in G.we have H n u =(H n u)WVis x—s—semipermutable.Since I f/n PI≤ d,it follows that G is P—supersoluble and this is a contra— diction.Thus. =1. Step 2 K is X—s—semipermutable in G. Since K is normal in P of order at most d,there ex— ists H∈tU such that K≤H≤P.Then K=P n uis s—semipermutable in G. Step 3 Let M be a maximal subgroup of P.Then n U=M f-I K is X-s—semipermutable in G. Since l l≤d andM n U<3P.there exists anH∈ tU such that M n K≤M n U≤日≤M.Then M n K: n K n H:H n K= n P n U:H n u.Thus. n K=M n u=H f3 U is X—s—semipermutable in G. Step 4 0。(G)n u≠l Suppose that 0 (G)n U=1 and let R be a minimal normal subgroup of G contained in U.Then R is not abe— lian.Since R is neither a P—group nor a P 一group by step 1.So,R n x=1 and hence R Cc(X).Let£be a mini— mal normal subgroup of R.Then L is a non—abelian simple subgroup.Let q be a prime divides order of L different fromP and Q a Sylow q-subgroup ofL. We claim that K n L permutes with Q.In fact,by step 2.K is 一5一semipermutable in G. Let T∈X (K).Then the Slyow q-subgroup Tq is al— so a Sylow q-subgroup of G,and K = K.On the other hand,Q is contained in some conjugate of Tq.By Lemma 1.1(5),without loss of generality,we may assume Q .Since L R CG( ),it follows that Q =Q=Tq n L is a Sylow q-subgroup of L.By lemma 1.3 n K =(,J n K)(L n Ca)=( n K)Q is a subgroup of L,that is, n K permutes with Q and our claim holds. 第1期 尤泽,等:有限群超可解的一些充分条件 101 Since Q is an arbitrary Sylow q-subgroup of L,and any Sylow q-subgroup of L is conjugate of Q,we have that L n Kpermutes with any conjugate of Q in L,that is(£n K)Q。=Q。( n K)for any a∈L.Clearly(£n K)口≠ L,so is not simple by lemma 1.2,a contradiction.This contradiction shows that U n D。(G)≠1 and step 4 holds. Step 5 d>P Assume that d=p.Then K is of order 1 or P.By step 4,U is p-soluble,hence P N U is contained in p-supersol— uble hypercentre.Therefore G is P—supersoluble,a contra- diction. Step 6 Finial contradiction. Let N be a minimal normal subgroup of G contained in U.Since I K I≤d.We have l N I≤d.Suppose that l Nl<d.We argue that G/N satisfies the hypothesis of the theorem.Clearly.1≤d/I NI<l P/Ⅳ1.Let H/T be a normal subgroup ofP/T of orderd/ITI.ThenH∈lv. It follows that H/N n f G/N)=H/N n U/N= (H n )/N,which is ..s semi.permutable in G/N.This shows that G/N satisfies the hypothesis of the claimed. Since l P/ N U/NI=l(P n )/NI≤d/l Nl。it of1. 1ows that G/N is P—supersoluble by minimality of G.Let I N l=d.Then N=K.So G/N is P—supersoluble. By[7,Kapitel VI,Staz8.6],we may suppose that N (P).Let M be a maximal subgroup ofP such thatN M.It is easy to see thatM N Kis a maximal subgroup of K and M n K≠1.By step 3.M n K is X—s-semiper— mutable in G.Take a subgroup T∈ (M n K).Then G =(M n K)Tand ofr any Sylow q-subgroup Q of T,where q≠P,we have(M N K)Q =Q (M N K)for some ∈ X.Thus,N n M=N n(M n K)Q (M n K)Q and so N n Mis normalized by Q .Clearly N n Mis a normal subgroup of P.so we have that N n G.This implies that N N M=1.and so N is of order P.Hence G is P-su— persoluble,which is a contradiction.This final contradic- tion completes the proof. 3 Some Corollaries of Theorem C Clearly,Theorems A and B can be obtained by Theo— rein C by choose =1.By Theorem C.we can also obtain some new descriptions of groups.For example,we have Corollary LetP∈Syl。(G)with IPI and X a soluble normal subgroup of G.Suppose that,for every maximal subgroup H of P,H n op(G)is X—s—semiper- mutable in G.Then G is p-supersoluble. Proof With a contradiction in mind.assume that G is not P-supersoluble.Write U= (G).By Theorem C, JP n U=P,that iS.P≤U。and so G=U.This means that every maximal subgroup of P is X-s-semipermutable in G.Then we conclude that G is P—supersoluble(cf. 『14,Theorem 1]). the Scientific Research Foundation of CUIT(J201512) References: [1] w Guo.The Theory of Classes of Groups[M]. Beijing-New York-Dordrecht—Boston—London:Sci— ence Press—Kluwer Academic Publishers,2000:1— 49. [2] B Huppe ̄.Endliche Gruppen I[M].Springer— Verlag Berlin-New York.1967. [3] Y Guo,I M Isaacs.Conditions onp—supergroups im— plying p-nilpotence or p-supersolvability[J]. Arch.Math,2015,105:215—222. [4] A Ballester—Bolinches,R Esteban—Romero,S Qiao. A note on a result of Guo and Isaaes aboutp·-super·· solvability of finite groups[J].Arch.Math.(Ba— se1),2016,106(6):501-506. [5] W E Deskins.On quasinormal subgroups of finite groups[J].Math.Z,1963,82:125-132. 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[12] Guo W,Shum K P,Skiba A N.X—semipermutable subgroups of ifnite groups[J].Chin,J.Algebra, 2007,28A(1):17-26. [15] I M Issaes.Semipermutable仃-subgroups[J]. Arch.Math,2014,102:1-6. [13] Hu B,Guo W.c-semipermutable subgroups of fi— [16] W Guo,Skiba A N,Shum K P.X—Quasinormal nite groups[J].Siberian Math.J,2007,48(1): 180—188. subgroups[J].Siberian Math.J,2007,48(4): 593—605. 有限群超可解的一些充分条件 尤 泽, 李保军 (成都信息工程大学应用数学学院,四川成都610025) 摘要:G是有限群且 是一个非空集合。若子群 在G中有补充 ,且对任取 中的元 ,H与 的任意Sylow 子群是 一置换的,子群日被称为是在G中X 半置换的.令d是一个小于P的阶的p一子群的阶.推广了s一半置换子 群的一些结果,利用X 半置换子群的性质进一步研究有限群,给出有限群超可解的一些结论.即可得到:对任意 的d阶正规子群日和G的可解正规子群 ,若日n 0 (G)在G中 一半置换的,则G是p一超可解的或者是 I P n 0 (G)l>d. 关键词:基础数学;代数学;有限群;p.超可解;X-s一半置换;p-群 

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