Existence results for KS3(v; 2, 4)s

A Kirkman square with index λ, latinicity μ, block size k and v points, KS_k(v; μ, λ), is a t × t array (t = λ(v − 1)/μ(k − 1)) defined on a v-set V such that (1) each point of V is contained in precisely μ cells of each row and column, (2) each cell of the array is either empty or contains a k subset of V, and (3) the collection of blocks obtained from the nonempty cells of the array is a (v, k, λ)-BIBD. The existence question for KS₂(v; μ, λ) has been completely selttled. We are interested in the next case k = 3. The case k = 3 and μ = λ = 1 appears to be quite difficult, although some existence results are available. For λ > 1 and μ ⩾ 1, the problem is more tractable. In this paper, we prove the existence of KS₃(v; 2, 4) for v ≡ 3 (mod 12), v ≡ 6 (mod 60) and v ≡ 9 (mod 96).     

The Compact Quantum Group Uq（2） （Ⅱ）

In this paper, we first prove that the θ-deformation Uθ（2） of U（2） constructed by Connes and Violette is our special case of the quantum group Uq（2） constructed in our previous paper. Then we will show that the set of truces on the C^＊ -algebra Uθ, θ irrational, is determined by the set of the truces on a subalgebra of Uθ.     

Existence of (2, 8) GWhD( v) and (4, 8) GWhD( v) with $${ v \equi v 0,1 (mod 8)}$$

(2, 8) Generalized Whist tournament Designs (GWhD) on v players exist only if . We establish that these necessary conditions are sufficient for all but a relatively small number of (possibly) exceptional cases. For there are at most 12 possible exceptions: {177, 249, 305, 377, 385, 465, 473, 489, 497, 537, 553, 897}. For there are at most 98 possible exceptions the largest of which is v = 3696. The materials in this paper also enable us to obtain four previously unknown (4, 8)GWhD(8n+1), namely for n = 16,60,191,192 and to reduce the list of unknown (4, 8) GWhD(8n) to 124 values of v the largest of which is v = 3696.      

Dade's Invariant Conjecture for the Symplectic Group Sp4(2 n ) and the Special Unitary Group SU4(22n ) in Defining Characteristic

In this article, we verify Dade's projective invariant conjecture for the symplectic group Sp₄(2 ⁿ ) and the special unitary group SU₄(2²ⁿ ) in the defining characteristic, that is, in characteristic 2. Furthermore, we show that the Isaacs–Malle–Navarro version of the McKay conjecture holds for Sp₄(2 ⁿ ) and SU₄(2²ⁿ ) in the defining characteristic, that is, Sp₄(2 ⁿ ) and SU₄(2²ⁿ ) are good for the prime 2 in the sense of Isaacs, Malle, and Navarro.     

Sieve methods in group theory II: the mapping class group

We prove that the set of non-pseudo-Anosov elements in the Torelli group is exponentially small. This answers a question of Kowalski (2008).     

Asymptotic Lefschetz fixed point theory for ANES(compact) maps

A number of new Lefschetz fixed point theorems are established for ANES(compact) maps. Also compact absorbing contraction maps are discussed.      

Fixed point theorems for paracompact convex sets (II)

The present paper is the continuation of [1]. Some further generalizations of the fixed point theorems in [2] are obtained by means of the results in [1]. Project supported by the National Natural Science Foundation of China     

^2F4（q2）与2-（v，k，3）对称设计

本文要证明不存在一个非平凡2-（v，k，3）对称设计，它的旗传递自同构群的基柱是^2F4（q2）     

环F4[v]/(v2+v)上DNA码

文章研究了环R=F_4[v]/(v~2+v)上的DNA码.基于环R上长度为n的线性码的代数结构,给出了环R上长度为n的线性码是可逆的DNA码的一个充要条件.同时,给出了环R上长度为n的线性码是可逆补DNA码的一个充要条件.     

New type B colorable S(2, 4, v) designs

An S(2, 4, v) design has a type B χ‐coloring if it is possible to assign one of χ colors to each point such that each block contains three points of one color and one point of a different color, and all χ colors are used. In this article we describe the constructions of type B χ‐colorable S(2, 4, v)s for (v, χ) = (61, 3), (100, 2) and (109, 3), and we give a new general construction. © 2007 Wiley Periodicals, Inc. J Combin Designs 15: 357–368, 2007     

Embeddings of Sλ(2, 4, v)

It is shown that the necessary condition for a given S_λ(2,4,u) to be embedded in some S_λ(2,4,v) as a subdesign, namely v ≥ 3u + 1, is also sufficient for the case of λ = 6. Combining this with the previously known results gives the same sufficiency for any positive integer λ. © 1994 John Wiley & Sons, Inc.     

Infinitesimal algebras for the hypercomplex system SO(4)//SO(2)

Two infinitesimal objects are constructed for the hypercomplex system with base SO(4)//SO(2). It is proved that they are finitely generated algebras. Generators are found for both algebras and commutation relations between the generators established in each case. It is proved that these algebras are of the Poincaré -Birkhoff-Witt type.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 3, pp. 427–429, March, 1990.     

Foundations of finite group theory for a (future) computer

good morning, Daisy. In 2027, your Development Committee approached me with a curious proposal. You, a dynamic AI system, were soon to be launched, and to demonstrate your capability to discover new mathematics with a minimum of instruction, they wanted a beginner’s course in elementary group theory (meant for     

单群F_4(2~n)的新刻画

设G为有限群,且满足M(G)=M(F4(2~n)),n1.则G有正规子群同构于F_4(2~n).特别地,若|G|=|F_4(2~n)|,则G≌F_4(2~n).     

李型单群2F4(q2)与2-((u),k,1)区组设计

本文证明了当2-((u),κ,1)设计的自同构群G的基柱soc(G)=2F4(q2)时,Buekenhaut-Delandtsheer-Doyen猜想成立,即自同构群G的基柱为Ree群2F4(q2)的区本原2-((u),k,1)设计必为点本原的.     

On the Spectrum of Steiner (v,k,t) Trades (II)

 A (v,k,t) trade T=T ₁−T ₂ of volume m consists of two disjoint collections T ₁ and T ₂ each containing m blocks (k-subsets) such that each t-subset is contained in the same number of blocks in T ₁ and T ₂. If each t-subset occurs at most once in T ₁, then T is called a Steiner (k,t) trade. In this paper, we continue our investigation of the spectrum S(k,2); that is, the set of allowable volumes of Steiner (k,t) trades when t=2. By using the concept of linked trades, we show that 2k+1∈S(k,2) precisely when k∈{3, 4, 7}. Received: February 28, 1997     

李型单群~2F_4(q~2)与2-(ν,κ,1)区组设计

本文证明了当2-(v,k,1)设计的自同构群G的基柱soc(G)=2F4(q2)时,Buekenhaut-Delandtsheer-Doyen猜想成立,即自同构群G的基柱为Ree群2F4(q2)的区本原2-(v,k,1)设计必为点本原的.