Showing papers in "Discrete Applied Mathematics in 1992"

TL;DR: A unified framework for the analysis of a class of random allocation processes that include the birthday paradox, the coupon collector problem, least-recently-used caching in memory management systems under the independent reference model and the move-to-front heuristic of self-organizing search is introduced.

TL;DR: A comparison of various heuristic methods for Steiner's problem in graphs is presented and shows how to develop efficient heuristic algorithms to find good approximate solutions.

TL;DR: For several NP-hard optimal linear labeling problems, including the bandwidth, the cutwidth, and the min-sum problem for graphs, a heuristic algorithm is proposed which finds approximative solutions to these problems in polynomial time.

TL;DR: A new method based on Tabu search techniques for finding a feasible course schedule based on daily quantums is described, which takes precedence and time windows requirements into account.

TL;DR: This work gives several characterizations for P4-sparse graphs and shows that they can be constructed from single-vertex graphs by a finite sequence of operations and implies that they admit a tree representation unique up to isomorphism.

TL;DR: Computational experience on problems with up to 50 jobs indicates that the proposed branch and bound algorithm is superior to other known algorithms.

TL;DR: This paper introduces a new data structure called a P4-tree, and uses the data structure as part of an algorithm to find the substitution decomposition of a graph in O(mα(m,n) time.

TL;DR: In this article, the Dutch Professional Football (US: soccer) Leagues are defined as a set of meetings between a number of clubs at preset dates under preset rules such that a problem can be divided in two subproblems: firstly developing a home-away schedule with oriented egde-colourings of complete graphs and secondly assigning the clubs to the Home-Away patterns with a clustering algorithm.

TL;DR: This work shows that this problem is solvable by a brute-force algorithm in Θ( n 2 2 n p log p ) time for a relation with p rows and n attributes, and proves two exponential lower bounds that hold even for the case where no explicit representation of the dependency set is needed.

TL;DR: A lattice theoretic approach is developed to study the properties of functional dependencies in relational databases, with particular attention to the analysis of the semilattice of closed sets, the lattice of all closure operations on a given set and to a new characterization of normal form relation schemes.

TL;DR: It is shown that the well-known independent set problem remains NP-complete even when restricted to graphs which contain no cycles of length less than cnk where n is the number of vertices in the graph, and c and k are constants satisfying c>0 and 0≤k<1.

TL;DR: This survey includes results on the integrity of specific families of graphs and combinations of graphs, relationships with other parameters, bounds, computational complexity, and some variations on the concept.

TL;DR: A simple linear time algorithm is given for three routing problems around a rectangle that finds routing in two or three layers for two-terminal nets specified on the sides of a rectangle using a theorem of Okamura and Seymour and a data structure developed by Suzuki, Ishiguro and Nishizeki.

TL;DR: It is demonstrated that γ and η are closely related to the principal partition and can be used to give a simple definition of both the principal partitions and the more recent refinements of it.

TL;DR: Four techniques to construct graphs of this type are described and it is shown that they produce the sparsest known graphs for several values of n and are minimum broadcast graphs.

TL;DR: New algorithms are presented for generating Cayley graphs in a more time-efficient manner than was previously possible and a second algorithm is provided for storing CayleyGraphs in a space- efficient manner, so that copies could be cheaply stored at each node of an interconnection network.

TL;DR: An O( n log n + dn ) time and space algorithm that finds an independent set of maximum weight for the interval model of G is presented and the best previous solution took time O ( n 3).

TL;DR: Study of product-shuffle networks, which are direct products of de Bruijn networks, as interconnection networks for parallel architectures, finds that they overcome certain computational deficiencies of butterfly- and shuffle-oriented networks, by containing as subnetworks moderate-size meshes and meshes of trees networks which butterfly-and- shuffle- oriented networks cannot emulate efficiently.

TL;DR: How the graph-theoretic concept of pathwidth is relevant in this approach to syntactic theory of Tesniere is discussed, and the importance of graphs with pathwidth ≤6 in connection with natural language processing is pointed out.

TL;DR: The relation between diameter andsuper-λ is established: enlarging the order n under the given maximum degree Δ and diameter D not only maximizes edge-connectivity, but also minimizes the number of minimum edge-cut sets, thus attaining super-λ.

TL;DR: Case data of a timetabling problem have been analysed and the special characteristics of the problem are the highly dense conflict matrix and the computer used in aiding the decision maker to arrive at a desirable timetable.

TL;DR: Algorithms are developed for enumerating all planar axial and rotational symmetrics of a biconnected outerplanar graph, and it is shown how to construct a drawing which simultaneously displays all these symmetries.

TL;DR: All variations of both point-to-point delivery problems are strongly NP-hard for all K≤2, but that there are polynomial algorithms in some cases if p is fixed, or if the underlying network is a grid with sources on one side, destinations on the other.

TL;DR: Some evidence is obtained for comparing the complexity of the restricted vertex coloring problem versus that of edge coloring and a number of results are arrived at about special cases that are either positive (polynomial solvability) or negative (NP-completeness proofs).

TL;DR: Observing that routing on a Cayley graphs is equivalent to a certain factoring problem in the associated group, a known powerful factoring technique in computational group theory is used to produce a fast efficient routing algorithm on the associated Cayley graph.

TL;DR: A necessary condition for the existence of long cycles in a graph involving the Laplacian spectrum of graphs is derived based on two theorems which relate the eigenvalues of a graph and the eigens of its induced subgraphs.

TL;DR: It is shown that deciding whether a given graph is a visibility graph is an NP-complete problem.

TL;DR: Some constructions giving large graphs with given degree and diameter are given, and for some diameters the asymptotic growth is improved and the quality of the constructions is improved.

TL;DR: In this paper, les auteurs analyse les contextes stratigraphiques et les evolutions architecturales which se succedent de 450-440 av. J.-C. (suite a un incendie generalise) aux alentours de 400 (un autre incendies ponctuel dans une habitation).

TL;DR: In this paper, a necessary and sufficient condition for a generalized hexagonal system in which every edge is not fixed is given, and a simple criterion to determine whether or not each hexagon of a complete generalized hexagon is resonant is given.