一类完全三部图的K1,3-因子大集

令G是一个有限图,H是G的一个子图.若V(H)=V(G),则称H为G的生成子图.图G的一个λ重F-因子,记为Sλ(F,G),是G的一个生成子图且可分拆为若干与F同构的子图(称为F-区组)的并,使得V(G)中的每一个顶点恰出现在λ个F-区组中.一个图G的λ重F-因子大集,记为LSλ(F G),是G中所有与F同构的子图的一个分拆{B_i}_i,使得每个B_i均构成一个Sλ(F,G).当λ=1时,λ可省略不写.本文中,我们证明了当v≡4 mod 24时,存在LS(K1,3,Kv,v,v).     

Boundary subspaces for the finite element method with Lagrange multipliers

Summary The paper is concerned with the problem of constructing compatible interior and boundary subspaces for finite element methods with Lagrange multipliers to approximately solve Dirichlet problems for secondorder elliptic equations. A new stability condition relating the interior and boundary subspaces is first derived, which is easier to check in practice than the condition known so far. Using the new condition, compatible boundary subspaces are constructed for quasiuniform triangular and rectangular interior meshes in two dimensions. The stability and optimal-order convergence of the finite element methods based on the constructed subspaces are proved.This work was supported by the Finnish National Research Council for Technical Sciences and by the Finnish-American ASLA-Fulbright Foundation     

利用辛空间上子空间构作(ω,r,d)-CFF(N,T)

利用辛空间上m维(m,s)型子空间的性质构作了(w,r,d)-CFF(N,T)系统,并利用子空间的计数定理计算了它的参数.一个(ω,r,d)-CFF(N,T)系统在许多领域有着极为广泛的应用.     

The doubly stochastic matrix equations x:aty= A and X Aty=t

For a doubly stochastic matrix A, each of the equations x:a^ty= A and X A^ty=^t is shown to have doubly stochastic solutions X and Y if and only if A lies in a subgroup of the semigroup of all doubly stochastic matrices of a given order. All elements of this semigroup which are left regular, right regular, or intra-regular are identified.     

叠加码的一些新构作

利用集合的并与直积运算建立了新的二元矩阵,从而在已有的叠加码的基础上构作了一些新的叠加码.     

A variable metric algorithm for unconstrained minimization without evaluation of derivatives

Summary This paper presents a modification of the BFGS-method for unconstrained minimization that avoids computation of derivatives. The gradients are approximated by the aid of differences of function values. These approximations are calculated in such a way that a complete convergence proof can be given. The presented algorithm is implementable, no exact line search is required. It is shown that, if the objective function is convex and some usually required conditions hold, the algorithm converges to a solution. If the Hessian matrix of the objective function is positive definite and satisfies a Lipschitz-condition in a neighbourhood of the solution, then the rate of convergence is superlinear.     

On the dimension of bivariate spline spaces of smoothnessr and degreed=3r+1

Summary We consider the well-known spaces of bivariate piecewise polynomials of degreed defined over arbitrary triangulations of a polygonal domain and possessingr continuous derivatives globally. To date, dimension formulae for such spaces have been established only whend3r+2, (except for the special case wherer=1 andd=4). In this paper we establish dimension formulae for allr1 andd=3r+1 for almost all triangulations.Dedicated to R. S. Varga on the occasion of his sixtieth birthdaySupported in part by National Science Foundation Grant DMS-8701121Supported in part by National Science Foundation Grant DMS-8602337     

Completing partial packings of bipartite graphs

Given a bipartite graph H and an integer n, let f(n;H) be the smallest integer such that any set of edge disjoint copies of H on n vertices can be extended to an H-design on at most n+f(n;H) vertices. We establish tight bounds for the growth of f(n;H) as n→∞. In particular, we prove the conjecture of Füredi and Lehel (2010) [4] that f(n;H)=o(n). This settles a long-standing open problem.     

Resolvable Maximum Packings with Quadruples

Let V be a finite set of v elements. A packing of the pairs of V by k-subsets is a family F of k-subsets of V, called blocks, such that each pair in V occurs in at most one member of F. For fixed v and k, the packing problem is to determine the number of blocks in any maximum packing. A maximum packing is resolvable if we can partition the blocks into classes (called parallel classes) such that every element is contained in precisely one block of each class. A resolvable maximum packing of the pairs of V by k-subsets is denoted by RP(v,k). It is well known that an RP(v,4) is equivalent to a resolvable group divisible design (RGDD) with block 4 and group size h, where h=1,2 or 3. The existence of 4-RGDDs with group-type hⁿ for h=1 or 3 has been solved except for (h,n)=(3,4) (for which no such design exists) and possibly for (h,n){(3,88),(3,124)}. In this paper, we first complete the case for h=3 by direct constructions. Then, we start the investigation for the existence of 4-RGDDs of type 2ⁿ. We shall show that the necessary conditions for the existence of a 4-RGDD of type 2ⁿ, namely, n 4 and n 4 (mod 6) are also sufficient with 2 definite exceptions (n=4,10) and 18 possible exceptions with n=346 being the largest. As a consequence, we have proved that there exists an RP(v,4) for v 0 (mod 4) with 3 exceptions (v=8,12 or 20) and 18 possible exceptions.Gennian Ge Researcher supported in part by YNSFC Grant 10001026 C.W.H. Lam Researcher supported by the National Science and Research Council of Canada Alan C.H. Ling Researcher supported by an ARO grant 19-01-1-0406 and a DOE grant Researcher supported by NSFC Grant 19831050