Searching for semifield flocks

Searches are performed in PG(3,q), q odd, for finding semifield and likeable flocks. For small values of q exhaustive searches are performed; limited searches are done for larger q. The main result of this paper is: In PG(3,27) any semifield flock is isomorphic either to the linear, Kantor–Knuth or Ganley flock. No new semifield or likeable flocks have been found.     

搜索三个目标

本文通过建立简洁而有效的搜索方法 ,证明了对于无穷多个n来说 ,三个目标的最优搜索问题的最小试验次数等于信息论下界 .同时也研究了上述问题的修正情形 ,证明了对于所有整数n来说 ,对应的最小试验次数或者等于信息论下界或者超过信息论下界 1次并且对于无穷多个区间 ,信息论下界均是可以达到的 .     

Searching for counterfeit coins

The well-known counterfeit problem asks for the minimum number of weighings necessary to determine all fake coins in a given set ofn coins. We derive a new upper bound when we know that at mostd coins are defective, improving a previous result of L. Pyber.     

Winners and losers: adding organisational value

As part of a major study into the success and survival of in-house OR groups in the UK the closure of 15 groups was investigated. Six selected continuing groups were also examined with the aim of identifying critical success and survival factors. Information was collected by interviews with key personnel, backed with questionnaire data. The results showed that external and organisational factors were a major cause of closure but that some factors within the control of a group could have been managed more vigorously. Suggestions for improving the effectiveness of OR groups and supporting dispersed practitioners are given.     

On the sum-of-ranks winner when losers are removed

Suppose that m alternatives are linearly ranked from best to worst by each of a number of judges, and that alternative x is the unique winner on the sum-of-ranks basis. It is shown that it is possible to construct a situation (with an appropriate number of judges) such that the initial winner x will be a sum-of-ranks loser within every proper subset of the original set of alternatives that contains x and at least one other alternative, except that x is the winner in exactly one subset that contains x and one other alternative.     

Searching for perfection on hypergraphs

In this paper we study the family of oriented transitive 3-hypergraphs that arise from cyclic permutations and intervals in the circle, in order to search for the notion of perfection on hypergraphs.     

Searching for extensible Korobov rules

Extensible lattice sequences have been proposed and studied in [F.J. Hickernell, H.S. Hong, Computing multivariate normal probabilities using rank-1 lattice sequences, in: G.H. Golub, S.H. Lui, F.T. Luk, R.J. Plemmons (Eds.), Proceedings of the Workshop on Scientific Computing (Hong Kong), Singapore, Springer, Berlin, 1997, pp. 209–215; F.J. Hickernell, H.S. Hong, P. L’Ecuyer, C. Lemieux, Extensible lattice sequences for quasi-Monte Carlo quadrature, SIAM J. Sci. Comput. 22 (2001) 1117–1138; F.J. Hickernell, H.Niederreiter, The existence of good extensible rank-1 lattices, J. Complexity 19 (2003) 286–300]. For the special case of extensible Korobov sequences, parameters can be found in [F.J. Hickernell, H.S. Hong, P. L’Ecuyer, C.Lemieux, Extensible lattice sequences for quasi-Monte Carlo quadrature, SIAM J. Sci. Comput. 22 (2001) 1117–1138]. The searches made to obtain these parameters were based on quality measures that look at several projections of the lattice. Because it is often the case in practice that low-dimensional projections are very important, it is of interest to find parameters for these sequences based on measures that look more closely at these projections. In this paper, we prove the existence of “good” extensible Korobov rules with respect to a quality measure that considers two-dimensional projections. We also report results of experiments made on different problems where the newly obtained parameters compare favorably with those given in [F.J. Hickernell, H.S. Hong, P. L’Ecuyer, C. Lemieux, Extensible lattice sequences for quasi-Monte Carlo quadrature, SIAM J. Sci. Comput. 22 (2001) 1117–1138].     

Searching for partially ordered structures

General methods are developed to search for minimal and dead-end payoff operators for a class of sources endowed with a partial order structure. It is shown that the results can be used in the design of experiments with automata and in the minimization of Boolean functions.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 2, pp. 253–260, February, 1992.     

两伪币的搜索问题

考虑两伪币的搜索问题: 给定外观相同的n个硬币, 其中有两个比较重的伪币, 通过等臂天平在尽可能少的称量次数下去找出两个伪币. L^{(2)}(n)为最坏情况下找到两伪币的最小称量步数. 对于任意的 n\geq2, 满足\lceil \log_3\binom{n}{2}\rceil \leq L^{(2)}(n)\leq\lceil \log_3\binom{n}{2}\rceil+1. 猜想信息理论下界均可达. 通过一个新的方法扩大了满足信息理论下界的n的取值范围.     

Searching for an edge in a graph

Consider the problem of determining the endpoints of an unknown edge x in a given graph G by asking questions of the form “Is vertex v an endpoint of edge e in G?”. Sharp upper and lower bounds are derived, and it is shown that determining the minimum number of questions in NP-complete.     

Searching for K3,3in linear time

It is shown that the search version of the subgraph homeomorphism problem for K_3,3 can be solved in time linear in the number of vertices of an arbitrary graph. This improves upon a previous result of Asano [1], who described a linear-time algorithm for the decision version of the problem and a quadratic-time algorithm for the search problem.     

Searching for joint gains in multi-party negotiations

We develop a constructive approach to multi-party negotiations over continuous issues. The method is intended to be used as a mediator's tool for step-by-step creation of joint gains in order to reach a Pareto-optimal agreement. During the mediation process, the parties are only required to answer relatively simple questions concerning their preferences; they do not have to reveal their utility functions completely. The method generates jointly improving directions to move along, and it is a non-trivial generalization of the recently proposed two-party methods. We give a mathematical analysis together with a numerical example, but also a practical basis for negotiation support in real-world settings.     

Tight Lower Bounds for Halfspace Range Searching

We establish two new lower bounds for the halfspace range searching problem: Given a set of n points in ℝ ^d , where each point is associated with a weight from a commutative semigroup, compute the semigroup sum of the weights of the points lying within any query halfspace. Letting m denote the space requirements, we prove a lower bound for general semigroups of [\varOmega\tilde](n^1-1/(d+1)/m^1/(d+1))\widetilde{\varOmega}(n^{1-1/(d+1)}/m^{1/(d+1)}) and for integral semigroups of [\varOmega\tilde](n/m^1/d)\widetilde{\varOmega}(n/m^{1/d}).     

Searching for a set of correlated patterns

New algorithms for searching simultaneously for a set of patterns in a text are suggested, for the special case where these patterns are correlated and have a common substring. This is then extended to the case where it could be more profitable to look for more than a single overlap, and a problem related to the generalization of this idea is shown to be NP-complete. Experimental results suggest that for this particular application, the suggested algorithm yields significant improvements over previous methods.     

证券组合选择有效子集的分类与搜索方法

本文在对证券组合选择有效子集的分类基础上,给出一个证券组合选择有效子集的搜索方法-逐个别法,并证明了它的有效性.