Trivial cup products in bounded cohomology of the free group via aligned chains

Abstract

We prove that the cup product of $\Delta$-decomposable quasimorphisms, Brooks quasimorphisms or Rolli quasimorphisms with any bounded cohomology class of arbitrary positive degree is trivial.

arXiv comment13 pages, 3 figures; remark deleted in section 1, typos corrected, v4: changes in sections 4 and 6, to appear in Forum Mathematicum