Compact differences of composition operators

Katherine Heller, Barbara D. MacCluer, Rachel J. Weir

When $\phi$ and $\psi$ are linear-fractional self-maps of the unit ball $B_N$ in ${\mathbb{C}}^N$, $N\ge 1$, we show that the difference $C_{\phi }-C_{\psi }$ cannot be non-trivially compact on eith…