Covering maps with separators

Simplicial ramified covering maps

In this paper we define the concept of a ramified covering map in the category of simplicial sets and we show that it has properties analogous to those of the topological ramified covering maps. We show that the geometric realization of a simplicial ramified covering map is a topological ramified covering map, and we also consider the relation with ramified covering maps in the category of simp...

Universal covering Maps and radial

Covering Small Independent Sets and Separators with Applications to Parameterized Algorithms

We present two new combinatorial tools for the design of parameterized algorithms. The first is a simple linear time randomized algorithm that given as input a d-degenerate graph G and an integer k, outputs an independent set Y , such that for every independent set X in G of size at most k, the probability that X is a subset of Y is at least (( (d+1)k

Covering dimension and finite-to-one maps

To Ken Kunen on the occasion of his retirement from teaching MSC: primary 54F45 secondary 54C10, 54G05

Regular quantizations and covering maps 1

Let M̃ → M be a holomorphic (unbranched) covering map between two compact complex manifolds, with b2(M̃) = 1. We prove that if M̃ and M both admit regular Kähler forms ω̃ and ω respectively then, up to homotheties, (M̃, ω̃) and (M, ω) are biholomorphically isometric.