The additive group of the rationals does not have an automatic presentation. - Todor Tsankov (J. Symb. Log., 2011)

Decidability of definability. - Manuel Bodirsky; Michael Pinsker; Todor Tsankov (J. Symb. Log., 2013)

Continuous Logic and Borel Equivalence Relations. - Andreas Hallbäck; Maciej Malicki; Todor Tsankov (J. Symb. Log., 2023)