Jarkko Kari

Jarkko J. Kari is a Finnish mathematician and computer scientist, known for his contributions to the theory of Wang tiles and cellular automata.

[1] Kari received his Ph.D. in 1990 from the University of Turku; his dissertation, supervised by Arto Salomaa.

[4] The same approach was later shown to lead to aperiodic sets of 13 tiles, the minimum known.

[5] Kari has also shown that the Wang tiling problem remains undecidable in the hyperbolic plane,[6] and has discovered sets of Wang tiles with additional mathematical properties.

In particular, in his thesis research, he showed that it is undecidable to determine whether a given cellular automaton rule in two or more dimensions is reversible.

Jarkko Kari, Alexander Kirillov and Tero Laihonen, University of Turku, 2019
An aperiodic set of 13 Wang tiles derived from Kari's research