Research

My research is currently in computing education. I am currently involved in two main research projects: ongoing assessment of the Embedded Ethics Education Initiative (E3I) and the use and impact of static analysis tools like PythonTA in introductory computing courses.

I was a PhD student in the Theory Group under the wonderful supervision of Toni Pitassi and Steve Cook. My area of research was computational complexity theory, and in particular I was part of Steve's attempt to use the Tree Evaluation Problem to separate the classical complexity complexity classes L and P. Before that, I had the pleasure of working under Janusz Brzozowski at the University of Waterloo.

Publications

• Diane Horton, David Liu, Sheila A. McIlraith, Steven Coyne, and Nina Wang. Do Embedded Ethics Modules Have Impact Beyond the Classroom? In Proceedings of the 55th ACM Technical Symposium on Computer Science Education V. 1, SIGCSE 2024, page 533–539, New York, NY, USA, 2024. Association for Computing Machinery.
• David Liu, Jonathan Calver, and Michelle Craig. A Static Analysis Tool in CS1: Student Usage and Perceptions of PythonTA. In Proceedings of the 26th Australasian Computing Education Conference, ACE ’24, page 172–181, New York, NY, USA, 2024. Association for Computing Machinery.
• Diane Horton, David Liu, Sheila A. McIlraith, and Nina Wang. Is More Better when Embedding Ethics in CS Courses? In Proceedings of the 54th ACM Technical Symposium on Computer Science Education V. 1, SIGCSE 2023, page 652–658, New York, NY, USA, 2023. Association for Computing Machinery.
• David Liu and Andrew Petersen. Static Analyses in Python Programming Courses. In Proceedings of the 50th ACM Technical Symposium on Computer Science Education, SIGCSE ’19, pages 666–671, New York, NY, USA, 2019. Association for Computing Machinery.
• Nick Parlante, Julie Zelenski, Benjamin Dicken, Ben Stephenson, Jeffrey L. Popyack, William M. Mongan, Kendall Bingham, Diane Horton, David Liu, and Allison Obourn. Nifty Assignments. In Proceedings of the 50th ACM Technical Symposium on Computer Science Education, SIGCSE ’19, pages 1230–1231, New York, NY, USA, 2019. Association for Computing Machinery.
• Yu Wu, Per Austrin, Toniann Pitassi, and David Liu. 2015. Inapproximability of Treewidth and Related Problems. In Proceedings of the 24th International Conference on Artificial Intelligence (IJCAI'15). AAAI Press, 4222–4228.
• Yu Wu, Per Austrin, Toniann Pitassi, and David Liu. 2014. Inapproximability of Treewidth, One-shot Pebbling, and Related Layout Problems. J. Artif. Int. Res. 49, 1 (January 2014), 569–600.
• David Liu. 2013. Pebbling Arguments for Tree Evaluation. Master's Thesis.
• Janusz Brzozowski and David Liu. 2013. Universal Witnesses for State Complexity of Boolean Operations and Concatenation Combined with Star. In: Jurgensen, H., Reis, R. (eds) Descriptional Complexity of Formal Systems. DCFS 2013. Lecture Notes in Computer Science, vol 8031. Springer, Berlin, Heidelberg.
• Janusz Brzozowski and David Liu. 2013. Universal Witnesses for State Complexity of Basic Operations Combined with Reversal. In Proceedings of the 18th international conference on Implementation and Application of Automata (CIAA'13). Springer-Verlag, Berlin, Heidelberg, 72–83.
• Janusz Brzozowski, Baiyu Li, and David Liu. 2012. Syntactic Complexities of Six Classes of Star-Free Languages. J. Autom. Lang. Comb. 17, 2 (March 2012), 83–105.