**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.

### Research Interests

## 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

- Tanja Hartmann, Jonathan Rollin, Ignaz Rutter, "
**Regular augmentation of planar graphs**" {url} Algorithmica, 73(2): 1–65, 2015 - 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)* - Daniel Hoske, Jonathan Rollin, Torsten Ueckerdt, Stefan Walzer, "
**Playing weighted Tron on trees**" {url} Discrete Mathematics, 338(12): 2341–2347, 2015 - Maria Axenovich, Jonathan Rollin, Torsten Ueckerdt, "
**Conditions on Ramsey non-equivalence**" {url} Journal of Graph Theory, 86(2): 159–192, 2017 - Maria Axenovich, Jonathan Rollin, Torsten Ueckerdt, "
**Chromatic number of ordered graphs with forbidden ordered subgraphs**" {url}] Accepted to Combinatorica - 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 - 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 - 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 - Jonathan Rollin, "
**Minimal Ordered Ramsey Graphs**" {url} submitted

### Dissertation

### 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