On estimates for the Besov norms of solutions to 3D subelliptic equations

We consider a class of linear subelliptic equations for functions of three variables. We obtain estimates, similar to the Schauder estimates, for the Besov norms of the derivatives of weak solutions to the equations under consideration with coefficients in suitable Besov spaces.     

On the independence property of first order theories and indiscernible sequences

We refute the strong version of Shelah’s conjecture about models of large cardinalities, the independence property, and indiscernible sequences. We find necessary and sufficient conditions for a theory to lack the independence property and present applications of these conditions.     

Degenerate parabolic systems of vector order Kolmogorov-type equations

We define a new class of degenerate \(\overrightarrow {2b}\)-parabolic systems of Kolmogorov-type equations with coefficients depending only on time. We also construct a fundamental matrix of solutions to a Cauchy problem for systems of this class and study its main properties.