After the number of vertices, Vertex Cover is the largest of the classical graph parameters and has more and more frequently been used as a separate parameter in parameterized problems, including problems that are not directly related to the Vertex Cover. Here we consider the TREEWIDTH and PATHWIDTH problems parameterized by k, the size of a minimum vertex cover of the input graph. We show that...

A cycle cover of a graph is a set of cycles such that every vertex is part of exactly one cycle. An L-cycle cover is a cycle cover in which the length of every cycle is in the set L ⊆ N. For most sets L, computing L-cycle covers of minimum weight is NP-hard and APX-hard. While computing L-cycle covers of maximum weight admits constant factor approximation algorithms (both for undirected and dir...

In the Line Cover problem a set of n points is given and the task is to cover the points using either the minimum number of lines or at most k lines. In Curve Cover, a generalization of Line Cover, the task is to cover the points using curves with d degrees of freedom. Another generalization is the Hyperplane Cover problem where points in d-dimensional space are to be covered by hyperplanes. Al...

We consider a scenario of distributed service installation in privately owned networks. Our model is a non-cooperative vertex cover game for k players. Each player owns a set of edges in a graph G and strives to cover each edge by an incident vertex. Vertices have costs and must be purchased to be available for the cover. Vertex costs can be shared arbitrarily by players. Once a vertex is bough...

We establish closed-form expansions for the universal edge elimination polynomial of paths and cycles and their generating functions. This includes closed-form expansions for the bivariate matching polynomial, the bivariate chromatic polynomial, and the covered components polynomial.

We show that any submodular minimization (SM) problem defined on linear constraint set with constraints having up to two variables per inequality, are 2-approximable in polynomial time. If the constraints are monotone (the two variables appear with opposite sign coefficients) then the problems of submodular minimization or supermodular maximization are polynomial time solvable. The key idea is ...

Set Cover is a well-studied problem with application in many fields. A well-known variant of this the Minimum Membership problem: Given set points and objects, objective to cover all while minimizing maximum number objects that contain any one point. dual Hitting stab an object contains. We study both these variants geometric setting various types plane, including axis-parallel line segments, s...

A simple path cover of a graph G is a collection ψ of paths in G such that every edge of G is in exactly one path in ψ and any two paths in ψ have at most one vertex in common. More generally, for any integer k ≥ 1, a Smarandache path k-cover of a graph G is a collection ψ of paths in G such that each edge of G is in at least one path of ψ and two paths of ψ have at most k vertices in common. T...

The question if a given partial solution to problem can be extended reasonably occurs in many algorithmic approaches for optimization problems. For instance, when enumerating minimal vertex covers of graph G=(V,E), one usually arrives at the decide set U?V (pre-solution), there exists cover S (i.e., S?V such that no proper subset is cover) with U?S (minimal extension U). We propose general, par...

We give an algorithm to morph between two planar drawings of a graph, preserving planarity, but allowing edges to bend. The morph uses a polynomial number of elementary steps, where each elementary step is a linear morph that moves each vertex in a straight line at uniform speed. Although there are planarity-preserving morphs that do not require edge bends, it is an open problem to find polynom...