11.55 (1990)

The answers to both 11.54 and 11.55 are affirmative, since the group $K_n$ of coloured braids is embeddable into the group of those automorphisms of the free group $F_n$ that act trivially modulo the derived subgroup of $F_n$, and this group is residually in the class of torsion-free nilpotent groups, for which the corresponding assertions are true (V. A. Roman’kov, Letter of October, 3, 1990). See also (V. G. Bardakov, Russ. Acad. Sci. Sbornik Math., 76, no. 1 (1993), 123–153).