T. Zamfirescu

activity

20032026

collaborators

8 papers

math.CO2026

On the m-point convexity

Wenzhi Liu, Wei Wang, Liping Yuan +1

Let $S \subset R^{d}$ $(d \geq 2)$ . A set $S$ is said to be $m$ -point convex, if for every $m$ distinct points in $S$ , at least one of the line-segments determined by them lie…

math.CO2026

The orthogonal connectedness of polyhedral surfaces

Julia Q. Du, Xuemei He, Xiaotian Song +3

Using the orthogonal connectedness, we introduce the notion of orthogonal decomposability of convex polytopes and study it in the case of Platonic and Archimedean solids. While doi…

math.CO2025

Excursions in Sylvester-Gallai land

Imre Barany, Julia Q. Du, Dan Schwarz +2

The Sylvester-Gallai theorem states that for a finite set of points in the plane, if every line determined by any two of these points also contains a third, then the set is necessa…

math.CO2025

Orthogonally connected sets

Xuemei He, Xiaotian Song, Liping Yuan +1

In this paper, we further investigate the orthogonally connected sets and establish necessary and sufficient conditions for a set to be staircase connected.

math.MG2019

Locating diametral points

Jin-ichi Itoh, Costin Vîlcu, Liping Yuan +1

Let $K$ be a convex body in $R^{d}$ , with $d = 2, 3$ . We determine sharp sufficient conditions for a set $E$ composed of $1$ , $2$ , or $3$ points of $bd K$ , to contain a…

math.GT2019

With respect to whom are you critical?

Jin-ichi Itoh, Costin Vîlcu, Tudor Zamfirescu

For any compact Riemannian surface $S$ and any point $y$ in $S$ , $Q_{y}^{- 1}$ denotes the set of all points in $S$ , for which $y$ is a critical point. We proved \cite{BIVZ} together…