# Goddyn, Luis A.

## Circular colouring the orthogonality graph ★★

Author(s): DeVos; Ghebleh; Goddyn; Mohar; Naserasr

Let denote the graph with vertex set consisting of all lines through the origin in and two vertices adjacent in if they are perpendicular.

**Problem**Is ?

Keywords: circular coloring; geometric graph; orthogonality

## A conjecture on iterated circumcentres ★★

Author(s): Goddyn

**Conjecture**Let be a sequence of points in with the property that for every , the points are distinct, lie on a unique sphere, and further, is the center of this sphere. If this sequence is periodic, must its period be ?

Keywords: periodic; plane geometry; sequence

## (2 + epsilon)-flow conjecture ★★★

**Conjecture**For every there exists an integer so that every -edge-connected graph has a -flow.

Keywords: edge-connectivity; flow