Email: reijo.jaakkola[at]tuni.fi
I'm a PhD student in mathematics at Tampere University, where I'm supervised by Antti Kuusisto and Lauri Hella.
My background is in the study of the satisfiability problems of fragments of firstorder logic. More specifically, I have studied the computational complexities of the satisfiability problems of various fragments using the tools of computational complexity theory. Recently I have been focusing on fragments that are descentents of modal logics.
Currently I am also focusing on trying to understand algorithms and heuristics that are being used to solve reallife (industrial) instances of constraint satisfaction problems. This also naturally leads to the study of the average case complexity of these problems, since industrial instances can be seen as being selected according to some polynomial time samplable distribution.
Research interests: fragments of firstorder logic, satisfiability problem, constructivism in mathematics.
Publications

Complexity of Polyadic Boolean Modal Logics: Model Checking and Satisfiability [Preprint]
Computer Science Logic 2023, February 1316, 2023, Warsaw (Poland)

Complexity Classifications via Algebraic Logic [Preprint]
Joint work with Antti Kuusisto.
Computer Science Logic 2023, February 1316, 2023, Warsaw (Poland)

Explainability via Short Formulas: the Case of Propositional Logic with Implementation [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)

Towards Model Theory of Ordered Logics: Expressivity and Interpolation [Preprint][Paper]
Joint work with Bartosz Bednarczyk.
47th International Symposium on Mathematical Foundations of Computer Science, August 2226, 2022, Vienna (Austria)

Uniform Guarded Fragments [Preprint][Paper]
25th International Conference on Foundations of Software Science and Computation Structures, April 27, 2022, Munich (Germany)

Ordered Fragments of FirstOrder Logic [Preprint][Paper]
46th International Symposium on Mathematical Foundations of Computer Science, August 2327, 2021, Tallinn (Estonia)
Preprints
 Convergence in the space of compact labeled metric spaces (Joint work with Antti Kykkänen.) [Preprint]
 Relating description complexity to entropy (Joint work with Antti Kuusisto and Miikka Vilander.) [Preprint]
 Firstorder logic with selfreference (Joint work with Antti Kuusisto.) [Preprint]
 An Extension of Trakhtenbrot's Theorem [Preprint]
 Complexity of the Ackermann fragment with one leading existential quantifier [Preprint]
Talks

Nopeat algoritmit ja laskennallinen vaativuus teoria (Invited talk)
[Slides in Finnish]IntegraatioFest 2022, October 2830, Tampere (Finland)

Firstorder logic with selfreference [Slides]
PhDs in Logic XIII, September 57, 2022, Turin (Italy)

Uniform Guarded Fragments [Slides]
25th International Conference on Foundations of Software Science and Computation Structures, April 27, 2022, Munich (Germany)

Complexity of Polyadic Boolean Modal Logics: Model Checking and Satisfiability
Logic and discrete mathematics seminar, Tampere University, Finland, 25 March 2022

Undecidability of the Halting Problem and Gödel's Incompleteness Theorems. [Slides][Video]
What is Computation? From Turing Machines to Black Holes and Neurons, Harvard GSAS MiniCourse, January 2022

Ordered fragments of firstorder logic [Slides]
Finnish Mathematical Days 2022

What is a fragment? [Slides]
Philosophy of Mathematics in Finland, Tampere, Finland, November 2021

Interpolation and fragments of firstorder logic
Logic and discrete mathematics seminar, Tampere University, Finland, 24 September 2021

Ordered fragments of firstorder logic [Slides]
46th International Symposium on Mathematical Foundations of Computer Science, Tallinn, Estonia, August 2021

Extensions of twovariable logic [Slides]
Logic and discrete mathematics seminar, Tampere University, Finland, 11 December 2020

Algebraic classifications for fragments of firstorder logic and beyond [Slides]
Logicians' Spring Gathering 2020, Tampere University, Finland, 8 May 2020
Thesis

Algebraic Fragments of FirstOrder Logic [Thesis]
Master's thesis, Tampere University, 2021, 45 pages
Awards

2022 Ernst Lindelöf Prize
Awarded for the best master's thesis in mathematics written in Finland during the academic year 20212022.
Quotes

But what we can't say we can't say, and we can't whistle it either.
Frank Ramsey

The method of showing a statement to be tautologous consists merely of constructing a table under it in the usual way and observing that the column under the main connective is composed entirely of 'T's.
Willard V. O. Quine

Young man, in mathematics you don't understand things. You just get used to them.
John von Neumann