# Wood, David R.

## Chromatic number of associahedron ★★

Author(s): Fabila-Monroy; Flores-Penaloza; Huemer; Hurtado; Urrutia; Wood

**Conjecture**Associahedra have unbounded chromatic number.

## Geometric Hales-Jewett Theorem ★★

**Conjecture**For all integers and , there is an integer such that for every set of at least points in the plane, if each point in is assigned one of colours, then:

- \item contains collinear points, or \item contains a monochromatic line (that is, a maximal set of collinear points receiving the same colour)

Keywords: Hales-Jewett Theorem; ramsey theory

## Generalised Empty Hexagon Conjecture ★★

Author(s): Wood

**Conjecture**For each there is an integer such that every set of at least points in the plane contains collinear points or an empty hexagon.

Keywords: empty hexagon

## Colouring $d$-degenerate graphs with large girth ★★

Author(s): Wood

**Question**Does there exist a -degenerate graph with chromatic number and girth , for all and ?

Keywords: degenerate; girth

## Forcing a 2-regular minor ★★

**Conjecture**Every graph with average degree at least contains every 2-regular graph on vertices as a minor.

Keywords: minors

## Fractional Hadwiger ★★

Author(s): Harvey; Reed; Seymour; Wood

**Conjecture**For every graph ,

(a)

(b)

(c) .

Keywords: fractional coloring, minors

## Forcing a $K_6$-minor ★★

Author(s): Barát ; Joret; Wood

**Conjecture**Every graph with minimum degree at least 7 contains a -minor.

**Conjecture**Every 7-connected graph contains a -minor.

Keywords: connectivity; graph minors

## Point sets with no empty pentagon ★

Author(s): Wood

**Problem**Classify the point sets with no empty pentagon.

Keywords: combinatorial geometry; visibility graph

## Number of Cliques in Minor-Closed Classes ★★

Author(s): Wood

**Question**Is there a constant such that every -vertex -minor-free graph has at most cliques?

## Big Line or Big Clique in Planar Point Sets ★★

Let be a set of points in the plane. Two points and in are *visible* with respect to if the line segment between and contains no other point in .

**Conjecture**For all integers there is an integer such that every set of at least points in the plane contains at least collinear points or pairwise visible points.

Keywords: Discrete Geometry; Geometric Ramsey Theory