In [1] Burger and Mynhardt introduced the idea of universal fixers. Let G = (V,E) be a graph with n vertices and G a copy of G. For a bijective function π : V (G) → V (G), define the prism πG of G as follows: V (πG) = V (G)∪ V (G) and E(πG) = E(G)∪E(G′)∪Mπ, where Mπ = {uπ(u) | u ∈ V (G)}. Let γ(G) be the domination number of G. If γ(πG) = γ(G) for any bijective function π, then G is called a un...

We propose a new nite cone covering algorithm for concave minimization over a polytope, in which the cones are de ned by extreme points of the polytope. The main novelties are the use of cones de ned by an arbitrary number of edges, and the subdivision process. This latter is shown to have a \descent property", i.e., all subcones are strictly better in some sense than the subdivided cone, which...

We construct CW spheres from the lattices that arise as the closed sets of a convex closure, the meet-distributive lattices. These spheres are nearly polytopal, in the sense that their barycentric subdivisions are simplicial polytopes. The complete information on the numbers of faces and chains of faces in these spheres can be obtained from the defining lattices in a manner analogous to the rel...

The concepts of covering and matching in fuzzy graphs using strong arcs are introduced and obtained the relationship between them analogous to Gallai’s results in graphs. The notion of paired domination in fuzzy graphs using strong arcs is also studied. The strong paired domination number γspr of complete fuzzy graph and complete bipartite fuzzy graph is determined and obtained bounds for the s...