Bavard's duality theorem for mixed commutator length

Morimichi Kawasaki, Mitsuaki Kimura, Takahiro Matsushita +1

Let $N$ be a normal subgroup of a group $G$. A quasimorphism $f$ on $N$ is $G$-invariant if $f(gx{g}^{-1})=f(x)$ for every $g\in G$ and every $x\in N$. The goal in this paper is…