Interval routing is a space-efficient routing method for computer networks. For the method to be practical, the routes it generates must be either shortest paths or not too much longer than the shortest paths. We answer the question ofwhat is the lower bound on the longest path that any interval routing scheme (IRS)may be able to generate for arbitrary planar graphs. In general, theworstcase pe...

We study the complexity of two Inverse Shortest Paths (ISP) problems with integer arc lengths and the requirement for uniquely determined shortest paths. Given a collection of paths in a directed graph, the task is to find positive integer arc lengths such that the given paths are uniquely determined shortest paths between their respective terminals. The first problem seeks for arc lengths that...

The longest path problem is the problem of finding a path of maximum length in a graph. Polynomial solutions for this problem are known only for small classes of graphs, while it is NP-hard on general graphs, as it is a generalization of the Hamiltonian path problem. Motivated by the work of Uehara and Uno in [22], where they left the longest path problem open for the class of interval graphs, ...

Given two sequences A = a 1 a 2 : : :a m and B = b 1 b 2 : : :b n , m n, over some alphabet , a common subsequence C = c 1 c 2 : : :c l of A and B is a sequence that can be obtained from both A and B by deleting zero or more (not necessarily adjacent) symbols. Finding a common subsequence of maximallength is called the Longest CommonSubsequence (LCS) Problem. Two new algorithms based on the wel...

The Hammersley process relates to the statistical properties of the maximum length of all up/right paths connecting random points of a given density in the unit square from (0,0) to (1,1). This process can also be interpreted in terms of the height of the polynuclear growth model, or the length of the longest increasing subsequence in a random permutation. The cumulative distribution of the lon...

We consider the following natural “above guarantee” parameterization of the classical Longest Path problem: For given vertices s and t of a graph G, and an integer k, the problem Longest Detour asks for an (s, t)-path in G that is at least k longer than a shortest (s, t)-path. Using insights into structural graph theory, we prove that Longest Detour is fixed-parameter tractable (FPT) on undirec...

Given a random permutation of the numbers 1, 2, . . . . n, let L, be the length of the longest descending subsequence of this permutation. Let F, be the minimal header (first element) of the descending subsequences having maximal length. It is known that EL,/&,,,, c and that c=2. However, the proofs that r=2 are far from elementary and involve limit processes. Several relationships between thes...

Let S = s1, s2, . . . , sn be an integer sequence. The longest increasing subsequence problem is to find an increasing subsequence of S with the longest length. By regarding S as a weight sequence of the vertices in a path, we can redefine the longest increasing subsequence problem on graphs as follows. Let G = (V,E) be a graph in which every vertex v ∈ V has a weight w(v). A longest increasing...

This paper addresses the problem of true delay estimation during high level design. The true delay is the delay of the longest sensitizable path in the resulting circuit, as opposed to the topological delay which is the delay of the longest path in the circuit. The existing delay estimation techniques either estimate the topological delay, which may be pessimistic if the longest path is unsensi...