Reijo Jaakkola

About Me

Welcome! I'm a fifth year PhD student in mathematics at Tampere University, supervised by Antti Kuusisto and Lauri Hella. I enjoy connecting theoretical foundations with real-world applications and exploring the intersections of machine learning, logic, and probability theory.

Machine Learning Mathematical Logic Probability Theory Complexity Theory Explainable AI

Publications

Peer-reviewed

1. Why this and not that? A Logic-based Framework for Contrastive Explanations [Publication] [Preprint]

   Joint work with Tobias Geibinger, Antti Kuusisto, Xinghan Liu and Miikka Vilander

   19th edition of the European Conference on Logics in Artificial Intelligence, 1-4 September 2025, Kutaisi, Georgia

2. Explainability via Short Formulas: the Case of Propositional Logic with Implementation [Publication]

   Joint work with Tomi Janhunen, Antti Kuusisto, Masood Feyzbakhsh Rankooh and Miikka Vilander

   Journal of Artificial Intelligence Research, Vol. 83 (2025), Article 8.

   Extends this workshop paper.

3. Relating Description Complexity to Entropy [Publication]

   Joint work with Antti Kuusisto and Miikka Vilander

   Journal of Computer and System Sciences

   Journal version of this conference paper.

4. Description Complexity of Unary Structures in First-Order Logic with Links to Entropy [Publication] [Preprint]

   Joint work with Antti Kuusisto and Miikka Vilander

   Computer Science Logic 2025, February 10-14, 2025, Amsterdam, Netherlands

5. Interpretable Classifiers for Tabular Data via Feature Selection and Discretization [Publication] [Preprint]

   Joint work with Tomi Janhunen, Antti Kuusisto, Masood Feyzbakhsh Rankooh and Miikka Vilander

   4th International Workshop of Data meets Applied Ontologies in Explainable AI, October 19, 2024, Santiago de Compostela, Spain

6. Short Boolean Formulas as Explanations in Practice [Publication] [Preprint]

   Joint work with Tomi Janhunen, Antti Kuusisto, Masood Feyzbakhsh Rankooh and Miikka Vilander

   18th Edition of the European Conference on Logics in Artificial Intelligence, September 20-22, 2023, Dresden, Germany

7. Relating Description Complexity to Entropy [Publication] [Preprint]

   Joint work with Antti Kuusisto and Miikka Vilander

   40th International Symposium on Theoretical Aspects of Computer Science, March 7-10, 2023, Hamburg, Germany

8. Complexity of Polyadic Boolean Modal Logics: Model Checking and Satisfiability [Publication] [Preprint]

   Computer Science Logic 2023, February 13-16, 2023, Warsaw, Poland

9. Complexity Classifications via Algebraic Logic [Publication] [Preprint]

   Joint work with Antti Kuusisto

   Computer Science Logic 2023, February 13-16, 2023, Warsaw, Poland

10. Explainability via Short Formulas: the Case of Propositional Logic with Implementation [Publication] [Preprint]

    Joint work with Tomi Janhunen, Antti Kuusisto, Masood Feyzbakhsh Rankooh and Miikka Vilander

    29th RCRA International Workshop on "Experimental Evaluation of Algorithms for solving problems with combinatorial explosion", September 5, 2022, Genova, Italy

11. Towards Model Theory of Ordered Logics: Expressivity and Interpolation [Publication] [Preprint]

    Joint work with Bartosz Bednarczyk

    47th International Symposium on Mathematical Foundations of Computer Science, August 22-26, 2022, Vienna, Austria

12. Uniform Guarded Fragments [Publication] [Preprint]

    25th International Conference on Foundations of Software Science and Computation Structures, April 2-7, 2022, Munich, Germany

13. Ordered Fragments of First-Order Logic [Publication] [Preprint]

    46th International Symposium on Mathematical Foundations of Computer Science, August 23-27, 2021, Tallinn, Estonia

Preprints

1. A monotone connection between model class size and description length [Preprint]

   Joint work with Antti Kuusisto and Miikka Vilander

2. Convergence in the space of compact labeled metric spaces [Preprint]

   Joint work with Antti Kykkänen

3. First-order logic with self-reference [Preprint]

   Joint work with Antti Kuusisto

Notes

1. An Extension of Trakhtenbrot's Theorem [Read Note]
2. Complexity of the Ackermann fragment with one leading existential quantifier [Read Note]

Selected Talks

1. Moderni selitettävä tekoälySlides
   SOTE-tekoäly ekosysteemin AI-aamu, 10 December, 2025, Webinaari
2. Why this and not that? A Logic-based Framework for Contrastive ExplanationsSlides
   19th edition of the European Conference on Logics in Artificial Intelligence, 1-4 September, 2025, Kutaisi, Georgia
3. Description Complexity of Unary Structures in First-Order Logic with Links to EntropySlides
   Computer Science Logic 2025, February 10-14, 2025, Amsterdam, the Netherlands
4. Expressing boundedness in static computational logicSlides
   Logic seminar, University of Helsinki, Finland, 29 January 2025
5. Description complexitySlides
   Seminar for young researchers, University of Jyväskylä, Finland, 27 November 2024
6. Uniform guarded fragments: interpolation and complexitySlides
   Workshop on Theory and Applications of Craig Interpolation and Beth Definability, April 22-23, 2024, Amsterdam, Netherlands
7. Formulas of propositional logic as interpretable classifiersSlides
   Mathematical Perspective on Machine Learning, University of Helsinki, Finland, 9 April 2024
8. Why do overparameterized neural networks generalize?Slides
   Seminar for young researchers, University of Jyväskylä, Finland, 6 March 2024
9. Explaining Classifiers and Data via Propositional LogicSlides
   Logic seminar, University of Helsinki, Finland, 22 November 2023
10. First-Order Logic with Game-Theoretic RecursionSlides
    Logic seminar, University of Helsinki, Finland, 20 April 2023
11. The Asymptotic Equipartition Property
    Seminar for young researchers, University of Jyväskylä, Finland, 29 March 2023
12. Relating Description Complexity to EntropySlides
    Research Seminar Logic and AI, TU Dresden, March 16, 2023, Dresden, Germany
13. First-Order Logic with Game-Theoretic RecursionSlides
    Fixed Points in Computer Science 2023, February 17, 2023, Warsaw, Poland
14. Complexity of Polyadic Boolean Modal Logics: Model Checking and SatisfiabilitySlides
    Computer Science Logic 2023, February 13-16, 2023, Warsaw, Poland
15. Complexity Classifications via Algebraic LogicSlides
    Computer Science Logic 2023, February 13-16, 2023, Warsaw, Poland
16. First order logic with game-theoretic recursion II
    Logic and discrete mathematics seminar, Tampere University, Finland, 13 January 2023
17. Nopeat algoritmit ja laskennallinen vaativuus teoria (Invited talk)Slides in Finnish
    IntegraatioFest 2022, October 28-30, Tampere, Finland
18. First-order logic with self-referenceSlides
    PhDs in Logic XIII, September 5-7, 2022, Turin, Italy
19. Uniform Guarded FragmentsSlides
    25th International Conference on Foundations of Software Science and Computation Structures, April 2-7, 2022, Munich, Germany
20. Complexity of Polyadic Boolean Modal Logics: Model Checking and Satisfiability
    Logic and discrete mathematics seminar, Tampere University, Finland, 25 March 2022
21. Undecidability of the Halting Problem and Gödel's Incompleteness TheoremsSlides Video
    What is Computation? From Turing Machines to Black Holes and Neurons, Harvard GSAS Mini-Course, January 2022
    Course website
22. Ordered fragments of first-order logicSlides
    Finnish Mathematical Days 2022
23. What is a fragment?Slides
    Philosophy of Mathematics in Finland, Tampere, Finland, November 2021
24. Interpolation and fragments of first-order logic
    Logic and discrete mathematics seminar, Tampere University, Finland, 24 September 2021
25. Ordered fragments of first-order logicSlides
    46th International Symposium on Mathematical Foundations of Computer Science, Tallinn, Estonia, August 2021
26. Extensions of two-variable logicSlides
    Logic and discrete mathematics seminar, Tampere University, Finland, 11 December 2020
27. Algebraic classifications for fragments of first-order logic and beyondSlides
    Logicians' Spring Gathering 2020, Tampere University, Finland, 8 May 2020

Theses

• Algebraic Fragments of First-Order Logic [Thesis]
  Master's thesis, Tampere University, 2021

Awards

• First Prize - Amplifying Financial AI with Quantum Data Augmentation
  Hanken Quantum x AI Hackathon 2025 [Website]
• Best Tech Solution - Unlocking ESG Insights
  Hanken Quantum Hackathon 2023 [Website]
• 2022 Ernst Lindelöf Prize
  Awarded for the best master's thesis in mathematics written in Finland during the academic year 2021-2022.

Professional Activities

• Research Visits
  • TU Wien, Host: Mantas Šimkus, Topic: Interpretable graph classifiers, 14-18.7.2025
  • TU Wien, Host: Magdalena Ortiz, Topic: Relating knowledge graphs and neural networks, 16-20.12.2024
  • TU Wien, Host: Thomas Eiter, Topic: Explaining AI via logic, 27.11.2023 - 1.12.2023
  • University of Wroclaw and TU Dresden, Host: Bartosz Bednarczyk, Topic: Model theory of ordered fragments, 10-23.3.2023
• I organized a session for Young Researchers at the Finnish Mathematical Days 2024. The goal of the session was twofold: (1) to provide an opportunity for PhD students to present their research area within mathematics; and (2) to showcase modern research topics in mathematics within Finland. List of talks can be found here.
• I have been a reviewer for various conferences (AAMAS 2022, IJCAI 2023, KR 2023, MFCS 2023, JELIA 2023, GandALF 2023, AAAI 2024, LICS 2024, KR 2024, AAMAS 2025, KR 2025, GandALF 2025, STACS 2026) and journals (LMCS, JLC).

Software

• RSCLASSIFIER [Download]

  A Python library which implements a machine learning algorithm for learning role set classifiers for classification tasks. Easy to use, efficient and produces highly interpretable and transparent models.

• Cont-Bouchaud model [Repository]

  Course project that I did for the course Statistical Physics 2.

Quotes that I Like