Showing papers in "Discrete Applied Mathematics in 1989"

TL;DR: An algorithm paradigm for solving NP- hard problems on graphs restricted to partial graphs of k -trees and given with an embedding in a k -tree is presented and illustrated by a sequence of examples.

TL;DR: This work has applications in crytography and coding theory since a reduction in the complexity of multiplying and exponentiating elements of GF(2n) is achieved for many values of n, some prime.

TL;DR: In this paper, the existence of large homogeneous (monochromatic) configurations of a certain kind under the condition that the size of the underlying set is large is investigated.

TL;DR: It is shown that all four versions of the problem of finding two disjoint paths from s to t such that the length of the longer path is minimized are strongly NP-complete.

TL;DR: It is shown that π 1 n n →C as n→∞, for some constant C, the probability that a random self-avoiding polygon of n steps on the three-dimensional cubic lattice is unknotted.

TL;DR: This paper investigates low complexity normal bases, gives a construction for such bases and applies it to a number of cases of interest.

TL;DR: Borders are given on these forwarding indices, in particular as a function of the connectivity of the graph, and calculate them for products of graphs and for some specific graphs.

TL;DR: A new combinatorial property of square factors in the infinite Thue-Morse word M 2 is given : every nontrivial factorization M 2 = w 1 w 2 implies that w 1 has a square suffix, or w 2 has asquare prefix.

TL;DR: A generalization of the Tutte polynomial that is defined for signed graphs to provide a link between knot theory and graph theory, and to explore a context embracing both subjects.

TL;DR: A new algorithm to output a list of occurrences of periodicities within a string, guaranteed to contain any periodicity which is leftmost and maximal, is presented.

TL;DR: The problem of determining the cutwidth of a graph, called the Min Cut Linear Arrangement problem, has applications in VLSI, for example in the minimization of interconnection channels in Weinberger arrays.

TL;DR: Interrelationships are shown among the complexities of computing the permanent and determinant of a matrix despite their similar looking formulae, the complexity of checking if a directed graph contains an even length cycle, and the number of perfect matchings in a graph using Pfaffian orientations.

TL;DR: This work shows how to derive close lower and upper bounds on the minimum number of function evaluations needed to find a local optimum in an arbitrary graph and applies these techniques to the hypercube to give insights into the class PLS and the gap between the average and worst-case behavior of local search.

TL;DR: This paper examines the facial structure of the 3-index assignment polytope (the convex hull of feasible solutions to the problem) with the aid of the intersection graph of the coefficient matrix of the problem's constraint set, and gives an O(n4) procedure for finding a facet-defining clique-inequality violated by a given noninteger solution to the linear programming relaxation of the3- index assignment problem.

TL;DR: A polynomial method for decomposing a graph into 2-bicritical components and Konig-Egervary components is described, which yields a minimum fractional node cover in which the number of nodes receiving the value 12 is minimized.

TL;DR: It is shown that the blossom algorithm for a maximum matching of a graph G over the vertex set V can be adapted to find a matching M maximizing ∑(w(x): x is saturated by M) for any w ϵ RV.

TL;DR: It is proved that for the binary symmetric trie the variance is asymptotically equal to 4.35…·n+nf(log2n) where n is the number of stored records and f(x) is a periodic function with a very small amplitude.

TL;DR: This paper provides further classes of digraphs in which two directed cycles in H make the H -colouring problem NP-hard, including both classes of dense and of sparseDigraphs.

TL;DR: This work uses Mellin transforms to obtain size estimates as integrals of meromorphic functions forsuffix trees, directed acyclic word graphs and related data structures, and finds that Poles on the real axis lead to exact formulae for the average sizes, while poles with nonzero imaginary part lead to very good estimates of the oscillations.

TL;DR: It is shown that for i >62; j ≥1 the C i,j problem is NP-complete for arbitrary graphs and a polynomial-time dynamic programming algorithm algorithm is exhibited for the Ci 1 problem on chordal graphs, for i ≥3.

TL;DR: It is shown that strong tree-cographs are Birkhoff graphs, a class of undirected graphs which can be derived from trees by a finite sequence of operations involving disjoint union and complementation.

TL;DR: This paper proves that s( L n 3 )=n for all n ≥ 7, with the possible exception of n = 8.

TL;DR: This paper designs a slightly more complicated scheme that uses the largest available bin size for small pieces, and selects bin sizes for large pieces based on a user-specified fill factor, and proves that this strategy guarantees a worst-case bound not exceeding 1.5+ ƒ 2 .

TL;DR: An optimal solution is constructed by using properties of oriented factorizations of complete graphs in a real case of sports scheduling problem.

TL;DR: A version of the gravitational method for linear programming, based on steepest descent gravitational directions, that requires no expensive initialization, and operates only with a small subset of locally active constraints at each step.

TL;DR: It is shown that the satisfiability of a class r 0 , s 0 -SAT implies the Satisfiability of classes r, s -S AT, for certain well-defined higher value of r and s .

TL;DR: It is shown that Teng and Tucker's algorithm can be implemented to run in O(n1.5) time overall using an interesting relationship between the time it takes to solve a q-colorability problem and the range of possible q to be searched for.

TL;DR: The concept of breaking up coherent algebras which embeds the given coherent algebra into a coherent algebra of a greater dimension and reduces the multiplicity of the algebra is introduced.

TL;DR: It is shown here that PA and qCC are consistent iff q≥ (m−1) m or m ≤3, where m is the number of candidates and q-Core Condition requires that whenever there exists a candidate such that no other candidate is preferred to him/her by a fraction of q or more of the voters, the elected candidate should have this property.

TL;DR: An attempt is made to characterize special classes of TDI systems on the basis of existence of totally unimodular active matrix sets of specific types and a new TDI system is introduced which contains as special cases certain interesting old and newTDI systems.