Research Group on Discrete Mathematics

Secretariat
Kollegiengebäude Mathematik (20.30)
Room 1.044

Institut für Algebra und Geometrie
Englerstr. 2
D-76131 Karlsruhe

Office hours:
Tu, Th, F 8:30-12:00

Tel.: +49 721 608 47412

Fax.: +49 721 608 46968

 Jonathan Rollin Office hour for students: Friday, 15:30-16:30 Room: 1.039 Kollegiengebäude Mathematik (20.30) Tel.: +49721 608 43784 Email: jonathan.rollin@kit.edu Karlsruher Institut für Technologie Fakultät für Mathematik Institut für Algebra und Geometrie Kaiserstr. 89-93 | 76133 Karlsruhe

Since April 2018 I am PostDoc with André Schulz at the University of Hagen.

I was a member of the research group on discrete mathematics since October 2013. In May 2017 I finished my PhD here and stayed in the group until March 2018. Before starting the PhD I studied computer sciences and mathematics here in Karlsruhe, where my main focus was already on graph theory and combinatorics.

I am interested in many areas of graph theory and combinatorics. Currently, I study different kinds of graph colorings and decompositions from an extremal point of view, which in particular includes graph Ramsey theory.

Latest research of mine focuses on ordered graphs, that is, graphs equipped with a linear ordering of the vertex set. I study how classical results from graph theory behave in the ordered setting.

Semester Titel Typ
Winter Semester 2017/18
Seminar
Summer Semester 2017
Winter Semester 2016/17
Summer Semester 2016
Winter Semester 2015/16
Summer Semester 2015
Summer Semester 2014
Winter Semester 2013/14

## Graph Colorings:

• chromatic number of (ordered) graphs under local constraints, conflict-free colorings, (1,r-1)-colorings

## Ramsey Theory:

• Ramsey equivalence, Ramsey multiplicity, ordered graph Ramsey theory

## Graph Decompositions:

• induced arboricity, {a,b}-factors

### Publications

1. Tanja Hartmann, Jonathan Rollin, Ignaz Rutter, "Regular augmentation of planar graphs" {url} Algorithmica, 73(2): 1–65, 2015
2. Maria Axenovich, Jonathan Rollin, "Brooks type results for conflict-free colorings and {a, b}-factors in graphs" {file} Discrete Mathematics, 338(12): 2295–2301, 2015 (corrected statement of Theorem 7)
3. Daniel Hoske, Jonathan Rollin, Torsten Ueckerdt, Stefan Walzer, "Playing weighted Tron on trees" {url} Discrete Mathematics, 338(12): 2341–2347, 2015
4. Maria Axenovich, Jonathan Rollin, Torsten Ueckerdt, "Conditions on Ramsey non-equivalence" {url} Journal of Graph Theory, 86(2): 159–192, 2017
5. Maria Axenovich, Jonathan Rollin, Torsten Ueckerdt, "Chromatic number of ordered graphs with forbidden ordered subgraphs" {url}] Accepted to Combinatorica
6. Anton Bernshteyn, Omid Khormali, Ryan R. Martin, Jonathan Rollin, Danny Rorabaugh, Songling Shan, Andrew J. Uzzell, "Regular colorings and factors of regular graphs" {url} submitted
7. Maria Axenovich, Daniel Goncalves, Jonathan Rollin, Torsten Ueckerdt, "The k-strong induced arboricity of a graph" {url} European Journal of Combinatorics, 67: 1–20, 2018
8. Maria Axenovich, Jonathan Rollin, Torsten Ueckerdt, "The chromatic number of ordered graphs with constrained conflict graphs" {url} Australasian Journal of Combinatorics, 69: 74–104, 2017
9. Jonathan Rollin, "Minimal Ordered Ramsey Graphs" {url} submitted

### Conference Talks

35'th Kolloquium über Kombinatorik, Paderborn, November, 4 - 5 2016
"Chromatic number of ordered graphs without forbidden ordered subgraphs"

6'th Polish Combinatorial Conference, Bedlewo, September 19 - 23, 2016
"Chromatic number of ordered graphs without forbidden ordered subgraphs"

Utrecht Combinatorics Workshop, Utrecht, November 7, 2014
"Brooks Type Results for Conflict-Free Colorings and {a,b}-factors in graphs"

### Workshops

Oberwolfach Seminar “Positional Games”, May 19 - 25, 2013

Rocky Mountain-Great Plains Graduate Research Workshop in Combinatorics, Ames IA, June 1 -13, 2015