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Vjekoslav Kovač

E-mail address:

Postal address:
Department of Mathematics
Faculty of Science
University of Zagreb
Bijenička cesta 30
10000 Zagreb
CROATIA

Office: A310

Research publications and preprints:

[43] Sharp estimates for Gowers norms on discrete cubes (with A. Beker and T. Crmarić), preprint, 22 pp, submitted for publication. [arXiv]
[42] On eventually greedy best underapproximations by Egyptian fractions, accepted for publication in J. Number Theory, 7 pp.
∫  The preprint contains a solution to a problem by Erdős and Graham, stated as Problem #206 on T. Blooms's website Erdős problems. The problem was originally stated here (p. 31).
∫  A nice popular discussion of the paper was written by R. Green on A Piece of the Pi.
[arXiv] [journal]
[41] On the set of points represented by harmonic subseries, accepted for publication in Amer. Math. Monthly, 17 pp.
∫  The preprint contains a solution to a problem by Erdős, Graham, and Straus, stated as Problem #268 on T. Blooms's website Erdős problems. The problem was originally stated here (p. 65). It was also mentioned here (p. 334) and here (p. 104-105).
∫  An ancillary Mathematica notebook is available here.
[arXiv] [journal]
[40] Coloring and density theorems for configurations of a given volume, preprint, 47 pp, submitted for publication.
∫  The preprint contains (among other things) a solution to a problem by Erdős and Graham, stated as Problem #189 on T. Blooms's website Erdős problems. The problem was originally stated here (p. 331) and here (p. 15). The most recent reference to the problem seems to be this book (p. 56). An illustration of a finite coloring that avoids rectangles of area 1 is here.
∫  This is an expanded version of an unpublished note titled Monochromatic boxes of unit volume (arXiv v1).
[arXiv]
[39] Large dilates of hypercube graphs in the plane (with B. Predojević), Anal. Math. (2024), 23 pp. [arXiv] [journal]
[38] A strong-type Furstenberg-Sárközy theorem for sets of positive measure, (with P. Durcik and M. Stipčić), J. Geom. Anal. 33 (2023), issue 8, article no. 255, 16 pp. [arXiv] [journal]
[37] Multi-parameter maximal Fourier restriction (with A. Bulj), J. Fourier Anal. Appl. 30 (2024), issue 3, article no. 26, 23 pp.
∫  The paper answers a question by Vitturi.
[arXiv] [journal]
[36] On binomial sums, additive energies, and lazy random walks, J. Math. Anal. Appl. 528 (2023), issue 1, article 127510, 13 pp.
∫  The paper contains a solution to an elementary problem originating in the work of de Dios Pont, Greenfeld, Ivanisvili, and Madrid. An ancillary Mathematica notebook is available here.
[arXiv] [journal]
[35] Asymptotic behavior of $L^p$ estimates for a class of multipliers with homogeneous unimodular symbols (with A. Bulj), Trans. Amer. Math. Soc. 376 (2023), no. 7, 4539-4567.
∫  The paper contains a solution to Problem 15 by Maz'ya and to a problem by Dragičević, Petermichl, and Volberg.
[arXiv] [journal]
[34] Bilinear embedding in Orlicz spaces for divergence-form operators with complex coefficients (with K. A. Škreb), J. Funct. Anal. 284 (2023), issue 9, article 109884, 32 pp. [arXiv] [journal]
[33] Sharp $L^p$ estimates of powers of the complex Riesz transform (with A. Carbonaro and O. Dragičević), Math. Ann. 386 (2023), 1081-1125.
∫  The paper contains a solution to a problem by Iwaniec and Martin.
[arXiv] [journal]
[32] Asymptotically sharp discrete nonlinear Hausdorff-Young inequalities for the SU(1,1)-valued Fourier products (with D. Oliveira e Silva and J. Rupčić), Q. J. Math. 73 (2022), no. 3, 1179-1188. [arXiv] [journal]
[31] Popular differences for right isosceles triangles, Electron. J. Combin. 28 (2021), no. 4, article P4.27, 10 pp.
∫  The paper contains a solution to a problem by Ackelsberg, Bergelson, and Best.
[arXiv] [journal]
[30] Trilinear embedding for divergence-form operators with complex coefficients (with A. Carbonaro, O. Dragičević, and K. A. Škreb), Adv. Math. 431 (2023), article 109239, 72 pp. [arXiv] [journal]
[29] Pointwise convergence of certain continuous-time double ergodic averages (with M. Christ, P. Durcik, and J. Roos), Ergodic Theory Dynam. Systems. 42 (2022), no. 7, 2270-2280. [arXiv] [journal]
[28] The density of sets containing large similar copies of finite sets (with K. Falconer and A. Yavicoli), J. Anal. Math. 148 (2022), 339-359. [arXiv] [journal]
[27] Density theorems for anisotropic point configurations, Canad. J. Math. 74 (2022), no. 5, 1244-1276. [arXiv] [journal]
[26] Convergence of ergodic-martingale paraproducts (with M. Stipčić), Statist. Probab. Lett. 164 (2020), article 108826, 6 pp.
∫  The paper is motivated by an open-ended question of Kakutani.
[arXiv] [journal]
[25] A Szemerédi-type theorem for subsets of the unit cube (with P. Durcik), Anal. PDE. 15 (2022), no. 2, 507-549.
∫  The paper contains a partial solution to a problem originating in the work of Cook, Magyar, and Pramanik.
[arXiv] [journal]
[24] Improving estimates for discrete polynomial averages (with R. Han, M. T. Lacey, J. Madrid, and F. Yang), J. Fourier Anal. Appl. 26 (2020), article 42, 11 pp.
∫  The paper contains a solution to a problem previously posed by Han, Lacey, and Yang.
[arXiv] [journal]
[23] Variational estimates for martingale paraproducts (with P. Zorin-Kranich), Electron. Commun. Probab. 24 (2019), paper no. 48, 14 pp. [arXiv] [journal]
[22] Fourier restriction implies maximal and variational Fourier restriction, J. Funct. Anal. 277 (2019), issue 10, 3355-3372.
∫  The paper is motivated by several questions by Müller, Ricci, and Wright.
∫  A nice discussion of the proof was written by M. Vitturi on his blog.
[arXiv] [journal]
[21] A variational restriction theorem (with D. Oliveira e Silva), Arch. Math. 117 (2021), 65-78. [arXiv] [journal]
[20] Boxes, extended boxes, and sets of positive upper density in the Euclidean space (with P. Durcik), Math. Proc. Cambridge Philos. Soc. 171 (2021), no. 3, 481-501. [arXiv] [journal]
[19] Characterizations of democratic systems of translates on locally compact abelian groups (with H. Šikić), Monatsh. Math. 189 (2019), no. 3, 459-485. [arXiv] [journal]
[18] A sharp nonlinear Hausdorff-Young inequality for small potentials (with D. Oliveira e Silva and J. Rupčić), Proc. Amer. Math. Soc. 147 (2019), no. 1, 239-253.
∫  An ancillary Mathematica notebook is available here.
[arXiv] [journal]
[17] On side lengths of corners in positive density subsets of the Euclidean space (with P. Durcik and L. Rimanić), Int. Math. Res. Not. 2018, no. 22, 6844-6869. [arXiv] [journal]
[16] Bellman functions and $L^p$ estimates for paraproducts (with K. A. Škreb), Probab. Math. Statist. 38 (2018), no. 2, 459-479.
∫  An ancillary Mathematica notebook is available here.
[arXiv] [journal]
[15] Power-type cancellation for the simplex Hilbert transform (with P. Durcik and C. Thiele), J. Anal. Math. 139 (2019) 67-82.
∫  The paper contains a (partial) solution to a problem originating in the work of T. Tao.
[arXiv] [journal]
[14] On the combined use of GW approximation and cumulant expansion in the calculations of quasiparticle spectra: The paradigm of Si valence bands (B. Gumhalter, V. Kovač, F. Caruso, H. Lambert, and F. Giustino), Phys. Rev. B. 94 (2016), no. 3, article 035103, 16 pp + 4 pp suppl. [arXiv] [journal]
[13] Norm variation of ergodic averages with respect to two commuting transformations (with P. Durcik, K. A. Škreb, and C. Thiele), Ergodic Theory Dynam. Systems 39 (2019), no. 3, 658-688.
∫  The paper contains a (partial) solution to a problem by Avigad and Rute (previously also asked by J. Bourgain).
[arXiv] [journal]
[12] On a trilinear singular integral form with determinantal kernel (with P. Gressman, D. He, B. Street, C. Thiele, and P.-L. Yung), Proc. Amer. Math. Soc. 144 (2016), no. 8, 3465-3477. [arXiv] [journal]
[11] Dyadic triangular Hilbert transform of two general functions and one not too general function (with C. Thiele and P. Zorin-Kranich), Forum Math. Sigma 3 (2015), e25, 27pp.
∫  The paper solves the dyadic model of a particular case of a problem by Demeter and Thiele.
[arXiv] [journal]
[10] Quantitative norm convergence of double ergodic averages associated with two commuting group actions, Ergodic Theory Dynam. Systems 36 (2016), no. 3, 860-874. [arXiv] [journal]
[9] From electrostatic potentials to yet another triangle center (with H. Abraham), Forum Geom. 15 (2015), 73-89. [arXiv] [journal]
[8] On the share of closed IL formulas which are also in GL (with V. Čačić), Arch. Math. Logic. 54 (2015), no. 7, 741-767. [arXiv] [journal]
[7] Sobolev norm estimates for a class of bilinear multipliers (with F. Bernicot), Commun. Pure Appl. Anal. 13 (2014), no. 3, 1305-1315. [arXiv] [journal]
[6] One modification of the martingale transform and its applications to paraproducts and stochastic integrals (with K. A. Škreb), J. Math. Anal. Appl. 426 (2015), no. 2, 1143-1163. [arXiv] [journal]
[5] A T(1) theorem for entangled multilinear dyadic Calderón-Zygmund operators (with C. Thiele), Illinois J. Math. 57 (2013), no. 3, 775-799. [arXiv] [journal]
[4] On a trilinear form related to the Carleson theorem, J. Math. Anal. Appl. 405 (2013), no. 1, 220-226.
∫  The paper answers a (dyadic) toy model of an endpoint question by Demeter.
[arXiv] [journal]
[3] Bellman function technique for multilinear estimates and an application to generalized paraproducts, Indiana Univ. Math. J. 60 (2011), no. 3, 813-846. [arXiv] [journal]
[2] Uniform constants in Hausdorff-Young inequalities for the Cantor group model of the scattering transform, Proc. Amer. Math. Soc. 140 (2012), no. 3, 915-926.
∫  The paper solves a (Cantor group) toy model of a problem by Muscalu, Tao, and Thiele.
[arXiv] [journal]
[1] Boundedness of the twisted paraproduct, Rev. Mat. Iberoam. 28 (2012), no. 4, 1143-1164.
∫  The paper contains a solution to a problem by Demeter and Thiele.
[arXiv] [journal]

Citeable extended abstracts:

[iii] Large copies of large configurations in large sets, Incidence Problems in Harmonic Analysis, Geometric Measure Theory, and Ergodic Theory. Oberwolfach Rep. 20 (2023), no. 25, 3 pp. [preprint] [journal]
[ii] A sharp nonlinear Hausdorff-Young inequality for small potentials, Real Analysis, Harmonic Analysis and Applications. Oberwolfach Rep. 14 (2017), no. 34, 2125-2128. [preprint] [journal]
[i] Multilinear singular integrals with entangled structure, Real Analysis, Harmonic Analysis and Applications. Oberwolfach Rep. 11 (2014), no. 34, 1885-1888. [preprint] [journal]

Talk slides:

Talk slides in Croatian:

Theses:

Advisorship of doctoral students:

Editorial and administrative work:

Lecture notes in English: