Some extremal problems for martingale transforms. II

This paper is a direct continuation of the paper with the same title (V. I. Vasyunin, P. B. Zatitskiy, Some extremal problem for martingale transforms. I, Zap. Nauchn. Semin. POMI, 527 (2023), 5–530). For this reason neither the introductory part nor the list of references are duplicated. However for the reader convenience, the formulas from the first paper that are cited here are collected in a special addendum at the end of the paper with their original numbers.
At this paper two new local foliations are investigated: minor pockets and rectangles. The emergence of such local foliations is illustrated by the further investigation of examples in which the boundary functions are polynomials of the third degree.