Huppert's Conjecture for Alternating groups

Projective special linear groups $PSL_4(q)$ are determined by the set of their character degrees

Let $G$ be a finite group and let $cd(G)$ be the set of all irreducible complex character degrees of $G$. It was conjectured by Huppert in Illinois J. Math. 44 (2000) that, for every non-abelian finite simple group $H$, if $cd(G)=cd(H)$ then $G\cong H\times A$ for some abelian group $A$. In this paper, we confirm the conjecture for the family of projective special linear groups $\textrm{PSL}_4(q)$ with $q\geq 13$.

The Simple Ree groups ${}^2F_4(q^2)$ are determined by the set of their character degrees

Let $G$ be a finite group. Let ${\rm{cd}}(G)$ be the set of all complex irreducible character degrees of $G.$ In this paper, we will show that if ${\rm{cd}}(G)={\rm{cd}}(H),$ where $H$ is the simple Ree group ${}^2F_4(q^2),q^2\geq 8,$ then $G\cong H\times A,$ where $A$ is an abelian group. This verifies Huppert's Conjecture for the simple Ree groups ${}^2F_4(q^2)$ when $q^2\geq 8.$

有限单群的余度同构问题 II

The codegree isomorphism problem for finite simple groups II

本文针对有限单群的特征标余度同构猜想，提出比以往逐情形处理更统一的方法，并证实该猜想对若干族单群成立。

对称群与交错群双重覆盖的分块 Navarro Alperin 权猜想

The Blockwise Navarro Alperin Weight Conjecture for Double Covers of Symmetric and Alternating Groups

本文证明了对称群与交错群双重覆盖的分块 Navarro Alperin 权猜想。

A note on the Navarro conjecture for alternating groups with abelian defect

In [7], G. Navarro proposed a refinement of the McKay conjecture involving a special class of Galois automorphisms. In [6] this new conjecture was verified by the author for the alternating groups A(n) when p=2. In this note the Navarro conjecture is verified for the p-singular characters of the principal block of the alternating groups in the case of abelian defect when p is odd.

On groups with the same character degrees as almost simple groups with socle sporadic simple groups

Let G be a finite group and cd(G) denote the set of complex irreducible character degrees of G. In this paper, we prove that if G is a finite group and H is an almost simple group whose socle is a sporadic simple group H0 such that cd(G) = cd(H), then G' = H0 and there exists an abelian subgroup A of G such that G/A is isomorphic to H. In view of Huppert's conjecture (2000), we also provide some examples to show that G is not necessarily a direct product of A and H, and hence we cannot extend this conjecture to almost simple groups.

Alternating sums over pi-subgroups

Dade's conjecture predicts that if p is a prime, then the number of irreducible characters of a finite group of a given p-defect is determined by local subgroups. In this paper we replace $p$ by a set of primes pi and prove a pi-version of Dade's conjecture for pi-separable groups. This extends the (known) p-solvable case of the original conjecture and relates to a pi-version of Alperin's weight conjecture previously established by the authors.

阿尔佩林重量猜想、伽罗瓦自同构、交替和与函子等价

Alperin's weight conjecture, Galois automorphisms, alternating sums, and functorial equivalences

本文通过函子等价方法，证明了块级伽罗瓦阿尔佩林重量猜想的等价性，并探讨了伽罗瓦共轭块的函子等价性。

The Navarro Conjecture for the alternating groups

Recently Navarro proposed a strengthening of the unsolved McKay conjecture using Galois automorphisms. We prove that the Navarro conjecture holds for the alternating groups when the prime p is odd.

On groups with the same character degrees as almost simple groups with socle the Mathieu groups

Let $G$ be a finite group and $cd(G)$ denote the set of complex irreducible character degrees of $G$. In this paper, we prove that if $G$ is a finite group and $H$ is an almost simple group whose socle is Mathieu group such that $cd(G) =cd(H)$, then there exists an Abelian subgroup $A$ of $G$ such that $G/A$ is isomorphic to $H$. This study is heading towards the study of an extension of Huppert's conjecture (2000) for almost simple groups.

对称群与交错群的双覆盖的RoCK块的精细Broué猜想

The refined Broué conjecture for RoCK blocks of double covers of symmetric and alternating groups

本文针对对称群与交错群双覆盖的RoCK $p$-块，证明Kleshchev和Livesey构造的Morita等价与精彩Rickard等价可下降到$p$-进整数环，验证了Kessar与Linckelmann提出的精细Broué阿贝尔亏群猜想。

非可解群的非线性特征度数具有相同不同素因子数

Non-solvable groups whose non-linear character degrees have the same number of different prime divisors

本文研究非可解群的非线性特征度数具有相同不同素因子数的性质，证明此类群在可解因子作用下仅限于特定几类群，并验证Huppert的ρ-σ猜想。

On the character degree graph of solvable groups

Let \(G\) be a finite solvable group, and let \(Δ(G)\) denote the \emph{prime graph} built on the set of degrees of the irreducible complex characters of \(G\). A fundamental result by P.P. Pálfy asserts that the complement $\barΔ(G)$ of the graph \(Δ(G)\) does not contain any cycle of length \(3\). In this paper we generalize Pálfy's result, showing that $\barΔ(G)$ does not contain any cycle of odd length, whence it is a bipartite graph. As an immediate consequence, the set of vertices of \(Δ(G)\) can be covered by two subsets, each inducing a complete subgraph. The latter property yields in …

Descent of splendid Rickard equivalences in alternating groups

We show that each block of an alternating group over an arbitrary complete discrete valuation ring is splendidly Rickard equivalent to its Brauer correspondent. This provides new evidence for a refined version of Broué's abelian defect group conjecture proposed by Kessar and Linckelmann.

Thompson's conjecture for alternating group

Let $G$ be a finite group, and let $N(G)$ be the set of sizes of its conjugacy classes. We show that if a finite group $G$ has trivial center and $N(G)$ equals to $N(Alt_n)$ or $N(Sym_n)$ for $n\geq 23$, then $G$ has a composition factor isomorphic to an alternating group $Alt_k$ such that $k\leq n$ and the half-interval $(k, n]$ contains no primes. As a corollary, we prove the Thompson's conjecture for simple alternating groups.

On Thompson's conjecture for alternating and symmetric groups

For a finite group $G$ denote by $N(G)$ the set of conjugesy class sizes of $G$. We show that every finite group $G$ with the property $N(G)=N(Alt_n), n>4$ or $N(G)=N(Sym_n), n>22$ is non-solvable.

Crossover Morita equivalences of spin representations of the symmetric and alternating groups

We prove the existence of Morita equivalences between the spin blocks at the extremal points of strings in the block-reduced crystal graph. When the parities of the core partitions are not preserved, these equivalences require crossovers, with a block of the symmtric group Morita equivalent to a block of the alternating group and vice versa. The result permits in improvement of the bound for Donovan's Conjecture given by Kessar.

On Thompson's conjecture for alternating group of large degree

For a finite group $G$, let $N(G)$ denote the set of conjugacy class sizes of $G$. We show that if every finite group $G$ with trivial center such that $N(G)$ equals to $N(Alt_n)$, where $n>1361$ and at least one of numbers $n$ or $n-1$ are decomposed into a sum of two primes, then $G\simeq Alt_n$.

Conjectures on the normal covering number of the finite symmetric and alternating groups

Let $γ(S_n)$ be the minimum number of proper subgroups $H_i$ of the symmetric group $S_n$ such that each element in $S_n$ lies in some conjugate of one of the $H_i.$ In this paper we conjecture that $$γ(S_n)=\frac{n}{2}\left(1-\frac{1}{p_1}\right) \left(1-\frac{1}{p_2}\right)+2,$$ where $p_1,p_2$ are the two smallest primes in the factorization of $n$ and $n$ is neither a prime power nor a product of two primes. Support for the conjecture is given by a previous result for $n=p_1^{α_1}p_2^{α_2},$ with $(α_1,α_2)\neq (1,1)$. We give further evidence by confirming the conjecture for integers of t…

交错群的鲁棒汤普森猜想

The Robust Thompson's Conjecture for Alternating Groups

本文证明了交错群中一个足够大的共轭类 C 的平方 C² 包含除单位元外的所有元素，从而验证了 Shalev 提出的鲁棒汤普森猜想，方法结合特征标界、组合消去与超压缩性理论。

Alternating Quotients of Fuchsian Groups

It is shown that any finitely generated non-elementary Fuchsian group has among its homomorphic images all but finitely many of the alternating groups. This settles in the affirmative a conjecture of Graham Higman.

Binary permutation groups: alternating and classical groups

We introduce a new approach to the study of finite binary permutation groups and, as an application of our method, we prove Cherlin's binary groups conjecture for groups with socle a finite alternating group, and for the $\mathcal{C}_1$-primitive actions of the finite classical groups. Our new approach involves the notion, defined with respect to a group action, of a `\emph{beautiful subset}'. We demonstrate how the presence of such subsets can be used to show that a given action is not binary. In particular, the study of such sets will lead to a resolution of many of the remaining open cases …

Alternating groups as products of cycle classes - II

Given integers $k,l\geq 2$, where either $l$ is odd or $k$ is even, let $n(k,l)$ denote the largest integer $n$ such that each element of $A_n$ is a product of $k$ many $l$-cycles. In 2008, M. Herzog, G. Kaplan and A. Lev conjectured that $\lfloor \frac{2kl}{3} \rfloor \leq n(k,l)\leq \lfloor \frac{2kl}{3}\rfloor+1$. It is known that the conjecture holds when $k=2,3,4$. Moreover, it is also true when $3\mid l$. In this article, we determine the exact value of $n(k,l)$ when $3\nmid l$ and $k\geq 5$. As an immediate consequence, we get that $n(k,l)<\lfloor \frac{2kl}{3}\rfloor$ when $k\geq 5$, w…

The Answers to a Problem and Two Conjectures about OD-Characterization of Finite Groups

In [Akbari and Moghaddamfar, Recognizing by order and degree pattern of some projective special linear groups, {\it Internat. J. Algebra Comput.}, 2012] the authors possed the following problem: \\ {\bf Problem.} {\it Is there a simple group which is $k$-fold OD-characterizable for $k\geq3\ ?$ } In this paper as the main result we give positive answer to the above problem and we introduce two simple groups which are $k$-fold OD-characterizable such that $k\geq6$. Also in [R. Kogani-Moghadam and A. R. Moghaddamfar, Groups with the same order and degree pattern, {\it Science China Mathematics}, …

On some conjectures related to finite nonabelian simple groups

In this note we provide some counterexamples for the conjecture of Moretó on finite simple groups, which says that any finite simple group $G$ can determined in terms of its order $|G|$ and the number of elements of order $p$, where $p$ the largest prime divisor of $|G|$. Moreover, we show that this conjecture holds for all sporadic simple groups and alternating groups $A_n$, where $n\neq 8, 10$. Some related conjectures are also discussed.

Group-theoretic remarks on Goldbach's conjecture

The famous strongly binary Goldbach's conjecture asserts that every even number $2n \geq 8$ can always be expressible as the sum of two distinct odd prime numbers. We use a new approach to dealing with this conjecture. Specifically, we apply the element order prime graphs of alternating groups of degrees $2n$ and $2n-1$ to characterize this conjecture, and present its six group-theoretic versions; and further prove that this conjecture is true for $p+1$ and $p-1$ whenever $p \geq 11$ is a prime number.

Alternating quotients of right-angled Coxeter groups

Let $W$ be a right-angled Coxeter group corresponding to a finite non-discrete graph $\mathcal{G}$ with at least $3$ vertices. Our main theorem says that $\mathcal{G}^c$ is connected if and only if for any infinite index quasiconvex subgroup $H$ of $W$ and any finite subset $\{ γ_1, \ldots , γ_n \} \subset W \setminus H$ there is a surjection $f$ from $W$ to a finite alternating group such that $f (γ_i) \notin f (H)$. A corollary is that a right-angled Artin group splits as a direct product of cyclic groups and groups with many alternating quotients in the above sense. Similarly, finitely gene…

Smallest nontrivial quotients of the commutator subgroup of braid groups

We prove that the smallest non-trivial quotients of the commutator subgroups of the braid groups are the alternating groups, proving a conjecture of Chudnovsky-Kordek-Li-Partin. Furthermore, we show that any minimal quotient map is the standard projection, composed with an automorphism of the alternating group.