Research

I use probability to describe complex systems such as epidemics, chemical reactions, and species competition.

2020: Primary investigator for NSF RAPID Grant 2028892: *Quarantined Networks and the Spread of COVID-19.*

2019 -- 2023: Primary investigator for NSF DMS Grant 2115936: *Multitype Particle Systems*.

2021

**33. Chase-escape on the configuration model**

arXiv *To appear in Electronic Communications in Probability*

Emma Bernstein*, Clare Hamblen*, Lily Reeves

**32. Safe reopening of university campuses is possible with COVID-19 vaccination**

Sheng Li, Samitha Samanarake, Matthew Zalesak

**31. Diffusion-limited annihilating systems and the icx order**

Riti Bahl*, Philip Barnet*, Tobias Johnson

2020

**30. Three-velocity coalescing ballistic annihilation**

Luis Benitez*, Maximus Redman*, Lily Reeves

**29. Modeling COVID-19 spread in small colleges**

Riti Bahl*, Nicole Eikmeier, Alexandra Fraser*, Felicia Keesing, Kukai Nakahata*, Lily Z. Wang

**28.** **Particle density in diffusion-limited annihilating systems**

Tobias Johnson, Hanbaek Lyu, David Sivakoff

2013—2019

**27.** **Parking on supercritical Galton-Watson trees**

Riti Bahl*, Philip Barnet*

**26. Chase-escape with death on trees**

Erin Beckman, Keisha Cook, Nicole Eikmeier, Sarai Hernandez-Torres

**25. Two-type annihilating systems on the complete and star graph**

Stochastic Processes and their Applications

Irina Cristali*, Yufeng Jiang*, Remy Kassem*, David Sivakoff, Grayson York*

**24. Critical percolation and A+B-->2A dynamics**

Journal of Statistical Physics

**23. SIR epidemics on evolving graphs**

Yufeng Jiang*, Remy Kassem*, Grayson York*, Rick Durrett

**22. The phase structure of asymmetric ballistic annihilation**

arXiv *To appear in Annals of Applied Probability*

Hanbaek Lyu

**21. The contact process on periodic trees**

Yufeng Jiang*, Remy Kassem*, Grayson York*, Brandon Zhao*, Xiangying Huang, Rick Durrett

**20. Cover time for the frog model on trees**

Christopher Hoffman, Tobias Johnson

**19. The frog model on trees with drift**

Electronic Communications in Probability

Erin Beckman, Natalie Frank*, Yufeng Jiang*, Si Tang

**18. Coexistence in chase escape**

Electronic Communications in Probability

Rick Durrett, Si Tang

**17. The upper threshold in ballistic annihilation**

Debbie Burdinski*, Shrey Gupta*

**16. Poisson percolation on the oriented square lattice**

Stochastic Processes and their Applications

Irina Cristali*, Rick Durrett

**15. Poisson percolation on the square lattice**

Irina Cristali*, Rick Durrett

**14. Parking on transitive unimodular graphs**

Janko Gravner, Hanbaeck Lyu, David Sivakoff

**13. Block size in Geometric(p)-biased permutations**

Electronic Communications in Probability

Irina Cristali*, Vinit Ranjan*, Jake Steinberg*, Erin Beckman, Rick Durrett, James Nolen

**12. Asymptotic shape of the Brownian frog model**

Electronic Journal of Probability

Erin Beckman, Emily Dinan, Rick Durrett, Ran Huo

**11. Infection spread for the frog model on trees**

Electronic Journal of Probability

Christopher Hoffman, Tobias Johnson

**10. Coalescing random walk on unimodular graphs**

Electronic Communications in Probability

Eric Foxall. Tom Hutchcroft

**9. The bullet problem with discrete speeds**

Electronic Communications in Probability

Brittany Dygert*, Christoph Kinzel*, Jennifer Zhu*, Annie Raymond, Erik Slivken

**8. Ewens sampling and invariable generation**

Combinatorics, Probability, and Computing

Gerandy Brito, Christopher Fowler, Avi Levy

**7. Stochastic orders and the frog model**

Annales de l'Institut Henri Poincaré

Tobias Johnson

**6. The critical density for the frog model is the degree of the tree**

Electronic Communications in Probability

Tobias Johnson

**5. Frog model wakeup time on the complete graph**

Rose-Hulman Journal of Undergraduate Research

Nikki Carter*, Brittany Dygert*, Stephen Lacina*, Collin Litterell*, Austin Stromme*

**4. Site recurrence for coalescing random walk**

Electronic Communications in Probability

Itai Benjamini, Eric Foxall, Ori Gurel-Gurevich, Harry Kesten

**3. From transience to recurrence with Poisson tree frogs**

Christopher Hoffman, Tobias Johnson

**2. Choices, intervals and equidistribution**

Electronic Journal of Probability

**1. Recurrence and transience for the frog model on trees**

Christopher Hoffman, Tobias Johnson

*undergraduate