共查询到20条相似文献,搜索用时 31 毫秒
1.
Let ? be a complete set of Sylow subgroups of a finite group G, that is, a set composed of a Sylow p-subgroup of G for each p dividing the order of G. A subgroup H of G is called ?-S-semipermutable if H permutes with every Sylow p-subgroup of G in ? for all p?π(H); H is said to be ?-S-seminormal if it is normalized by every Sylow p-subgroup of G in ? for all p?π(H). The main aim of this paper is to characterize the ?-MS-groups, or groups G in which the maximal subgroups of every Sylow subgroup in ? are ?-S-semipermutable in G and the ?-MSN-groups, or groups in which the maximal subgroups of every Sylow subgroup in ? are ?-S-seminormal in G. 相似文献
2.
Given a multiplicative band of idempotents S in a ring R, for all e,f∈S the ∇-product e
∇
f=e+f+fe−efe−fef is an idempotent that lies roughly above e and f in R just as ef and fe lie roughly below e and f. In this paper we study ∇-bands in rings, that is, bands in rings that are closed under ∇, giving various criteria for ∇ to be associative, thus making the band a skew lattice. We also consider when a given band S in R generates a ∇-band. 相似文献
3.
Dongyuan Yao 《K-Theory》1996,10(3):307-322
Let A be an Abelian category and B be a thick subcategory of A. Let D
b(B) denote the derived category of cohomologically bounded chain complexes of objects in A and D
B
b
(A) denote the derived category of cohomologically bounded chain complexes of objects in A with cohomology in B. We give two if and only if conditions for equivalence of D(B) and D
B
b
(A), and we give an example where D
b
(B) and D
B
b
(A) are not equivalent. 相似文献
4.
Let G be a finite group, E a normal subgroup of G and p a fixed prime. We say that E is p-hypercyclically embedded in G if every p-G-chief factor of E is cyclic. A subgroup H of G is said to satisfy Π-property in G if |G∕K:NG∕K((H∩L)K∕K)| is a π((H∩L)K∕K)-number for any chief factor L∕K in G; we say that H has Π*-property in G if H∩Oπ(H)(G) has Π-property in G. In this paper, we prove that E is p-hypercyclically embedded in G if and only if some classes of p-subgroups of E have Π*-property in G. Some recent results are extended. 相似文献
5.
Juncheol Han 《代数通讯》2013,41(9):3551-3557
Let R be a ring with identity 1, I(R) be the set of all nonunit idempotents in R, and M(R) be the set of all primitive idempotents and 0 of R. We say that I(R) is additive if for all e, f ∈ I(R) (e ≠ f), e + f ∈ I(R), and M(R) is additive in I(R) if for all e, f ∈ M(R)(e ≠ f), e + f ∈ I(R). In this article, the following points are shown: (1) I(R) is additive if and only if I(R) is multiplicative and the characteristic of R is 2; M(R) is additive in I(R) if and only if M(R) is orthogonal. If 0 ≠ ef ∈ I(R) for some e ∈ M(R) and f ∈ I(R), then ef ∈ M(R), (2) If R has a complete set of primitive idempotents, then R is a finite product of connected rings if and only if I(R) is multiplicative if and only if M(R) is additive in I(R). 相似文献
6.
A general summability method is considered for functions from Herz spaces Kαp,r (?d ). The boundedness of the Hardy–Littlewood maximal operator on Herz spaces is proved in some critical cases. This implies that the maximal operator of the θ ‐means σθ T f is also bounded on the corresponding Herz spaces and σθ T f → f a.e. for all f ∈ K–d /p p,∞ (?d ). Moreover, σθ T f (x) converges to f (x) at each p ‐Lebesgue point of f ∈ K–d /p p,∞ (?d ) if and only if the Fourier transform of θ is in the Herz space Kd /p p ′,1 (?d ). Norm convergence of the θ ‐means is also investigated in Herz spaces. As special cases some results are obtained for weighted Lp spaces. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
Let 1 ≤ p ≤ ∞. A subset K of a Banach space X is said to be relatively p ‐compact if there is an 〈xn 〉 ∈ ls p (X) such that for every k ∈ K there is an 〈αn 〉 ∈ lp ′ such that k = σ∞n=1 αn xn . A linear operator T: X → Y is said to be p ‐compact if T (Ball (X)) is relatively p ‐compact in Y. The set of all p ‐compact operators Kp (X, Y) from X to Y is a Banach space with a suitable factorization norm κp and (Kp , κp ) is a Banach operator ideal. In this paper we investigate the dual operator ideal (Kd p , κd p ). It is shown that κd p (T) = πp (T) for all T ∈ B (X, Y) if either X or Y is finite‐dimensional. As a consequence it is proved that the adjoint ideal of Kd p is Ip ′, the ideal of p ′‐integral operators. Further, a composition/decomposition theorem Kd p = Πp K is proved which also yields that (Πmin p )inj = Kd p . Finally, we discuss the density of finite rank operators in Kd p and give some examples for different values of p in this respect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
Let W be a finite Coxeter group, P a parabolic subgroup of W, and N W (P) the normalizer of P in W. We prove that every element in N W (P) is strongly real in N W (P), and that every irreducible complex character of N W (P) has Frobenius-Schur indicator 1. 相似文献
9.
Given 1≤ p,q < ∞, let BLpLq be the class of all Banach lattices X such that X is isometrically lattice isomorphic to a band in some Lp(Lq)-Banach lattice. We show that the range of a positive contractive projection on any BLpLq-Banach lattice is itself in BLpLq. It is a consequence of this theorem and previous results that BLpLq is first-order axiomatizable in the language of Banach lattices. By studying the pavings of arbitrary BLpLq-Banach lattices by finite dimensional sublattices that are themselves in this class, we give an explicit set of axioms for
BLpLq. We also consider the class of all sublattices of Lp(Lq)-Banach lattices; for this class (when p/q is not an integer) we give a set of axioms that are similar to Krivine’s well-known axioms for the subspaces of Lp-Banach spaces (when p/2 is not an integer). We also extend this result to the limiting case q = ∞. 相似文献
10.
Let brk(C4;Kn, n) be the smallest N such that if all edges of KN, N are colored by k + 1 colors, then there is a monochromatic C4 in one of the first k colors or a monochromatic Kn, n in the last color. It is shown that brk(C4;Kn, n) = Θ(n2/log2n) for k?3, and br2(C4;Kn, n)≥c(n n/log2n)2 for large n. The main part of the proof is an algorithm to bound the number of large Kn, n in quasi‐random graphs. © 2010 Wiley Periodicals, Inc. J Graph Theory 67: 47‐54, 2011 相似文献
11.
Kosuke Ono 《Journal of Mathematical Analysis and Applications》2005,310(2):347-361
Consider the Cauchy problem in odd dimensions for the dissipative wave equation: (□+∂t)u=0 in with (u,∂tu)|t=0=(u0,u1). Because the L2 estimates and the L∞ estimates of the solution u(t) are well known, in this paper we pay attention to the Lp estimates with 1p<2 (in particular, p=1) of the solution u(t) for t0. In order to derive Lp estimates we first give the representation formulas of the solution u(t)=∂tS(t)u0+S(t)(u0+u1) and then we directly estimate the exact solution S(t)g and its derivative ∂tS(t)g of the dissipative wave equation with the initial data (u0,u1)=(0,g). In particular, when p=1 and n1, we get the L1 estimate: u(t)L1Ce−t/4(u0Wn,1+u1Wn−1,1)+C(u0L1+u1L1) for t0. 相似文献
12.
Let S={x1,…,xn} be a set of n distinct positive integers. For x,y∈S and y<x, we say the y is a greatest-type divisor of x in S if y∣x and it can be deduced that z=y from y∣z,z∣x,z<x and z∈S. For x∈S, let GS(x) denote the set of all greatest-type divisors of x in S. For any arithmetic function f, let (f(xi,xj)) denote the n×n matrix having f evaluated at the greatest common divisor (xi,xj) of xi and xj as its i,j-entry and let (f[xi,xj]) denote the n×n matrix having f evaluated at the least common multiple [xi,xj] of xi and xj as its i,j-entry. In this paper, we assume that S is a gcd-closed set and . We show that if f is a multiplicative function such that (f∗μ)(d)∈Z whenever and f(a)|f(b) whenever a|b and a,b∈S and (f(xi,xj)) is nonsingular, then the matrix (f(xi,xj)) divides the matrix (f[xi,xj]) in the ring Mn(Z) of n×n matrices over the integers. As a consequence, we show that (f(xi,xj)) divides (f[xi,xj]) in the ring Mn(Z) if (f∗μ)(d)∈Z whenever and f is a completely multiplicative function such that (f(xi,xj)) is nonsingular. This confirms a conjecture of Hong raised in 2004. 相似文献
13.
Friedrich Kasch 《代数通讯》2013,41(4):1459-1478
ABSTRACT We define “regular” for maps in a Hom group. This notion specializes to the well-known notions of (Von Neumann) regular in rings and modules. A map f ∈ Hom R (A,M) is regular if and only if Ker(f) ?⊕ A and Im(f) ?⊕ M. There exists a unique maximal regular End(M)-End(A)-submodule in Hom R (A,M). We study regularity in Hom R (A 1 ⊕ A 2, M 1 ⊕ M 2). The existence of a regular function Hom R (A,M) implies the existence of projective summands of Hom R (A,M) End R (A) and of End R ( M ) Hom R (A,M). We consider regularity in endomorphism rings, and generalize a theorem of Ware-Zelmanowitz. We examine connections between the maximum regular bimodule and other substructures of Hom, mention two generalizations of regularity, and raise some questions. 相似文献
14.
For a natural number n and a prime power q the general, special, projective general and projective special linear groups are denoted by GLn(q), SLn(q), PGLn(q) and PSLn(q), respectively. Using conjugacy classes of elements in GLn(q) in terms of irreducible polynomials over the finite field GF(q) we demonstrate how the set of order elements in GLn(q) can be obtained. This will help to find the order of elements in the groups SLn(q), PGLn(q) and PSLn(q). We also show an upper bound for the order of elements in SLn(q). 相似文献
15.
Let Lct(G) denote the set of all lengths of closed trails that exist in an even graph G. A sequence (t
1,..., t
p
) of elements of Lct(G) adding up to |E(G)| is G-realisable provided there is a sequence (T
1,..., t
p
) of pairwise edge-disjoint closed trails in G such that T
i
is of length T
i
for i = 1,..., p. The graph G is arbitrarily decomposable into closed trails if all possible sequences are G-realisable. In the paper it is proved that if a ⩾ 1 is an odd integer and M
a,a
is a perfect matching in K
a,a
, then the graph K
a,a
-M
a,a
is arbitrarily decomposable into closed trails.
相似文献
16.
Let E,F be two Banach spaces,B(E,F),B+(E,F),Φ(E,F),SΦ(E,F) and R(E,F) be bounded linear,double splitting,Fredholm,semi-Frdholm and finite rank operators from E into F,respectively. Let Σ be any one of the following sets:{T ∈Φ(E,F):Index T=constant and dim N(T)=constant},{T ∈ SΦ(E,F):either dim N(T)=constant< ∞ or codim R(T)=constant< ∞} and {T ∈ R(E,F):Rank T=constant< ∞}. Then it is known that Σ is a smooth submanifold of B(E,F) with the tangent space TAΣ={B ∈ B(E,F):BN(A)-R(A) } for any A ∈Σ. However,for ... 相似文献
17.
Xiaoyu Chen 《代数通讯》2013,41(2):731-745
A subgroup H of a finite group G is said to satisfy Π-property in G if for every chief factor L/K of G, |G/K: NG/K(HK/K ∩ L/K)| is a π(HK/K ∩ L/K)-number. A subgroup H of G is called Π-supplemented in G if there exists a subgroup T of G such that G = HT and H ∩ T ≤ I ≤ H, where I satisfies Π-property in G. In this article, we investigate the structure of a finite group G under the assumption that some primary subgroups of G are Π-supplemented in G. The main result we proved improves a large number of earlier results. 相似文献
18.
In the previous researches [2,3] b-integer and b-decimal parts of real numbers were introduced and studied by M.H. Hooshmand. The b-parts real functions have many interesting number theoretic explanations, analytic and algebraic properties, and satisfy the functional equation f (f(x) + y - f(y)) = f(x). These functions have led him to a more general topic in semigroups and groups (even in an arbitrary set with a binary operation [4] and the following functional equations have been introduced: Associative equations:
f(xf(yz))=f(f(xy)z),f(xf(yz))=f(f(xy)z)=f(xyz)