On convex complexity measures, with S. Jukna, A. Kulikov and P. Pudlák. To appear in TCS.

Non-comutative circuits and the sum of squares problem, with A. Wigderson and A. Yehudayoff. Submitted.

An asymptotic bound on integer sums of squares, with A. Wigderson and A. Yehudayoff. Draft.

Arithmetic complexity in algebraic extensions, with A. Yehudayoff, submitted.

Monotone separations for constant degree polynomials, with A. Yehudayoff, Information Processing Letters,   110,1 (2009), 1 - 3.

Proof complexity of polynomial identities, with I. Tzameret, CCC '09: Proceedings of the 2009 24th Annual IEEE Conference on Computational Complexity, (2009), 41 - 51.

Kreisel's conjecture with minimality principle,  Journal of Symbolic Logic 74,3 (2009) 976-988.

On lengths of proofs in non-classical logics, Annals of Pure and Applied Logic 157 (2009) 194 - 205.

Lower bounds for modal logics,  Journal of Symbolic Logic  72,3 (2007) 941-958.

A lower bound for intuitionistic logic,  Annals of Pure and Applied Logic 146 (2007) 72 - 90.

Theories very close to PA where Kreisel's conjecture is false, Journal of Symbolic Logic 72 (2007)  123-137.

On hierarchies of universal predicates,  ArXiv, (2007).