The letters 64 in silver characters, around which a silver circle, surrounded by a thicker blue round letter CCass Alexandru (they/them)(\(f,l) -> f.l@cs.rptu.de) “c” “alexandru”

Photo of Cass Alexandru

I am a PhD student at the Working Group Programming Languages at the RPTU Kaiserslautern-Landau, supervised by Ralf Hinze. I am co-supervised by Jurriaan Rot and Niels van der Weide, both at Radboud University Nijmegen. I will be available for Post-Docs starting around Fall 2027. My current research topic is the application of categorical semantics of (dependent) type theory to writing intrinsically correct total algorithms using structured recursion. More specifically, I am investigating recursive coalgebras and algorithmic duality.

Research Interests

I am interested in the application of the full breadth of the theoretical arsenal to the problem of designing theoretically rigorous and ergonomic verified functional programming languages, including but not limited to:

  • datatype-generic programming
  • recursion schemes
  • cubical and directed type theory
  • substructural type systems
  • embedded domain-specific languages
  • compiler construction
  • staged compilation
  • SMT, ATP & decision procedures
  • editor-time code generation & annotation
  • proof/program synthesis

Further areas I am interested in:

  • generative (property-based) testing, combinatorial species
  • recursive definition as a principle
  • symmetry-elimination for state-space reduction in ATP

Papers

Talks

Theses
  • “Intrinsically correct sorting using bialgebraic semantics”. Master’s thesis, Radboud University, 2023.
    BibLaTex 
     @thesis{alexandru_intrinsically_2023,
         author = {Alexandru, Cass},
         title = {Intrinsically correct sorting using bialgebraic semantics},
         institution = {Radboud University},
         type = {mathesis},
         year = {2023},
         file = {https://www.cs.ru.nl/masters-theses/2023/C_Alexandru___Intrinsically_correct_sorting_using_bialgebraic_semantics.pdf},
         url = {https://www.cs.ru.nl/masters-theses#2023},
         }
  • “Specifying Loops with Contracts”. Bachelor’s thesis, LMU Munich, 2019.
    BibLaTex 
     @thesis{alexandru_specifying_2019,
         author = {Alexandru, Cass},
         title = {Specifying Loops with Contracts},
         subtitle = {Reasoning about loops as recursive procedures},
         institution = {LMU Munich},
         type = {bathesis},
         year = {2019},
         file = {https://www.sosy-lab.org/research/bsc/2019.Alexandru.Specifying_Loops_With_Contracts.pdf},
         url = {https://www.sosy-lab.org/research/bib/Year/2019.html#AlexandruLoopContracts}
         }

Teaching

I have been a course assistant for the following courses:

I have been a group supervisor for the following courses:

During my (under)graduate studies, I was a TA for the following courses:

I was also a project supervisor for the following courses:

Supervised Theses

I was the working supervisor for the following theses:

Service

I serve as the main PhD student representative in the RPTU senate for Kaiserslautern in the academic year 2025-26 (link). I served as the main PhD student representative for computer science in 2024-25, and again in 2025-26 (link).

Unpublished Notes

Online presence

I go by cxandru on most online forums, and also use the same profile icon everywhere, so I should be relatively easy to spot. My accounts on selected forums: