Recent Submissions

• Implementing data-dependent triangulations with higher order delaunay triangulations ﻿

(Multidisciplinary Digital Publishing Institute (MDPI), 2017-12-01)
Article
Restricted access - publisher's policy
The Delaunay triangulation is the standard choice for building triangulated irregular networks (TINs) to represent terrain surfaces. However, the Delaunay triangulation is based only on the 2D coordinates of the data points, ...
• Distance 2-domination in prisms of graphs ﻿

(2017-01-01)
Article
Open Access
A set of vertices D of a graph G is a distance 2-dominating set of G if the distance between each vertex u ¿ ( V ( G ) - D ) and D is at most two. Let ¿ 2 ( G ) denote the size of a smallest distance 2 -dominating set of ...
• On Hamiltonian alternating cycles and paths ﻿

(2018-03)
Article
Open Access
We undertake a study on computing Hamiltonian alternating cycles and paths on bicolored point sets. This has been an intensively studied problem, not always with a solution, when the paths and cycles are also required to ...
• Carathodory's theorem in depth ﻿

(2017-07-01)
Article
Open Access
Let X be a finite set of points in RdRd . The Tukey depth of a point q with respect to X is the minimum number tX(q)tX(q) of points of X in a halfspace containing q. In this paper we prove a depth version of Carathéodory’s ...
• Characteristic polynomials of production matrices for geometric graphs ﻿

(2017-08-01)
Article
Open Access
An n×n production matrix for a class of geometric graphs has the property that the numbers of these geometric graphs on up to n vertices can be read off from the powers of the matrix. Recently, we obtained such production ...
• Internally perfect matroids ﻿

(2017-06-16)
Article
Open Access
In 1977 Stanley proved that the $h$-vector of a matroid is an $\mathcal{O}$-sequence and conjectured that it is a pure $\mathcal{O}$-sequence. In the subsequent years the validity of this conjecture has been shown for a ...
• Stabbing segments with rectilinear objects ﻿

(2017-09-15)
Article
Open Access
Given a set S of n line segments in the plane, we say that a region R¿R2 is a stabber for S if R contains exactly one endpoint of each segment of S. In this paper we provide optimal or near-optimal algorithms for ...
• On perfect and quasiperfect dominations in graphs ﻿

(2017-02-27)
Article
Open Access
A subset S ¿ V in a graph G = ( V , E ) is a k -quasiperfect dominating set (for k = 1) if every vertex not in S is adjacent to at least one and at most k vertices in S . The cardinality of a minimum k -quasiperfect ...
• Stabbing circles for sets of segments in the plane ﻿

(2017-03-13)
Article
Open Access
Stabbing a set S of n segments in the plane by a line is a well-known problem. In this paper we consider the variation where the stabbing object is a circle instead of a line. We show that the problem is tightly connected ...
• General properties of c-circulant digraphs ﻿

(1988)
Article
Open Access
A digraph is said to be a c-circulant if its adjacency matrix is c-circulant. This paper deals with general properties of this family of digraphs, as isomorphisms, regularity, strong connectivity, diameter and the relation ...
• Production matrices for geometric graphs ﻿

(2016)
Article
Open Access
We present production matrices for non-crossing geometric graphs on point sets in convex position, which allow us to derive formulas for the numbers of such graphs. Several known identities for Catalan numbers, Ballot ...
• New results on stabbing segments with a polygon ﻿

(2015-01-01)
Article
Open Access
We consider a natural variation of the concept of stabbing a set of segments with a simple polygon: a segment s is stabbed by a simple polygon P if at least one endpoint of s is contained in P, and a segment set S is stabbed ...