共查询到20条相似文献,搜索用时 15 毫秒
1.
Woonghee Tim Huh Ganesh JanakiramanPeter L. Jackson Nidhi Sawhney 《Operations Research Letters》2003,31(5):366-374
This paper studies minimizing the flow time of a cyclic schedule for repeated identical jobs, where one job is started/completed in each cycle, subject to the schedule achieving maximum throughput. We propose a branch and bound method for a single machine problem, and use this method to derive an improved lower bound for the multiple machine problem. 相似文献
2.
Georg Gati 《Discrete Applied Mathematics》1982,4(3):175-180
We solve a combinatorial problem that arises in determining by a method due to Engeler lower bounds for the computational complexity of algorithmic problems. Denote by Gd the class of permutation groups G of degree d that are iterated wreath products of symmetric groups, i.e. G = Sdh?11?1Sd0 with Πh?1i=0di = d for some natural number h and some sequence (d0,…,dh?1) of natural numbers greater than 1. The problem is to characterize those G = Sdh?11?1Sd0 in Gd on which k(G):=log|G|/max0≤i≤h?1log(di!) assumes its maximum. Our solution consists of two necessary conditions for this, namely that d0≤d1≤?≤dh and that dh is the largest prime divisor of d. Consequently, if d is a prime power, say d = ph with p prime, then a necessary and sufficient condition is that di = p, 0 ≤ i ≤ h ? 1. 相似文献
3.
Jorma Kaarlo Merikoski 《BIT Numerical Mathematics》1979,19(1):39-42
A lower boundn
–1
i,k
aik for the Perron eigenvalue of a symmetric non-negative irreducible matrixA=(a
ik) is studied and compared with certain other lower bounds. 相似文献
4.
The commutativity degree of a finite group G, denoted by Pr(G), is the probability that a randomly chosen pair of elements of G commute. The object of this paper is to derive a lower bound for Pr(G) and study some of its consequences towards characterizing G. 相似文献
5.
6.
Nathan Linial 《Discrete Mathematics》1976,15(3):297-300
Let G=(V, E) be a block of order n, different from Kn. Let m=min {d(x)+d(y): [x, y]?E}. We show that if m?n then G contains a cycle of length at least m. 相似文献
7.
8.
9.
10.
Christoph Maas 《Journal of Computational and Applied Mathematics》1984,10(1):65-69
The interval number i(G) of a graph G with n vertices is the lowest integer m such that G is the intersection graph of some family of sets I1,…,In with every Ii being the union of at most m real intervals. In this article a lower bound for i(G) is proved followed by some considerations about the construction of graphs that are critical with respect to the interval number. 相似文献
11.
E. Gudiño 《Linear algebra and its applications》2010,433(1):233-240
We show that the spectral radius ρ(D) of a digraph D with n vertices and c2 closed walks of length 2 satisfies Moreover, equality occurs if and only if D is the symmetric digraph associated to a -regular graph, plus some arcs that do not belong to cycles. As an application of this result, we construct new sharp upper bounds for the low energy of a digraph, which extends Koolen and Moulton bounds of the energy to digraphs. 相似文献
12.
It is proved that the distortion of any knotted curve in ℝ3 is greater than 4.76. This improves the result by John M. Sullivan and Elizabeth. Denne. Bibliography: 3 titles. 相似文献
13.
Joseph F. Grcar 《Linear algebra and its applications》2010,433(1):203-220
Four essentially different interpretations of a lower bound for linear operators are shown to be equivalent for matrices (involving inequalities, convex sets, minimax problems, and quotient spaces). Properties stated by von Neumann in a restricted case are satisfied by the lower bound. Applications are made to rank reduction, s-numbers, condition numbers, and pseudospectra. In particular, the matrix lower bound is the distance to the nearest matrix with strictly contained row or column spaces, and it occurs in a condition number formula for any consistent system of linear equations, including those that are underdetermined. 相似文献
14.
On the equivalence of the max-min transportation lower bound and the time-indexed lower bound for single-machine scheduling problems 总被引:1,自引:0,他引:1
New observations are made about two lower bound schemes for single-machine min-sum scheduling problems. We find that the strongest
bound of those provided by transportation problem relaxations can be computed by solving a linear program. We show the equivalence
of this strongest bound and the bound provided by the LP relaxation of the time-indexed integer programming formulation. These
observations lead to a new lower bound scheme that yields fast approximation of the time-indexed bound. Several techniques
are developed to facilitate the effective use of the new lower bound in branch-and-bound. Numerical experiments are conducted
on 375 benchmark problems of the total weighted tardiness problem from OR-Library. Results obtained with our new method are
spectacular; we are able to solve all 125 open problems to optimality. 相似文献
15.
16.
In this paper we determine the topology of three-dimensional complete orientable Riemannian manifolds with a uniform lower bound of sectional curvature whose volume is sufficiently small. 相似文献
17.
Yu. A. Aminov 《Journal of Mathematical Sciences》1994,69(1):825-828
A closed orientable four-dimensional manifoldM
4, whose sectional curvatures satisfy –1 K 1, is considered. If the product of the curvatures of orthogonal area elements is nonnegative and if at least at one point all the curvatures are different from zero, then the estimate vol(M
4) > (4/9)2 is obtained for the volume ofM
4. A theorem on the local structure of a manifold with small volume whose curvatures at every point are of the same sign is established.Translated from Ukrainskii Geometricheskii Sbornik, No. 34, pp. 3–8, 1991. 相似文献
18.
J.M. Varah 《Linear algebra and its applications》1975,11(1):3-5
For a matrix A which is diagonally dominant both by rows and by columns, we give bounds for 6A-161 and 6A-16∞, which then can be used to give a lower bound for the smallest singular value. We also show that these bounds can be attained, and show how the result can be extended to block matrices. 相似文献
19.
20.
Dejan Kolaric 《Proceedings of the American Mathematical Society》2008,136(4):1273-1284
Let be a closed polydisc or ball in , and let be a quasi-projective algebraic manifold which is Zariski locally equivalent to , or a complement of an algebraic subvariety of codimension in such a manifold. If is an integer satisfying , then every holomorphic map from a neighborhood of to with rank at every point of can be approximated uniformly on by entire maps with rank at every point of .