A Dichotomy for Derivations on $\mathscr O_n$
A Dichotomy for Derivations on $\mathscr O_n$
Let \mathscr O_n be the Cuntz algebra generated by s_1, \cdots ,s_n , and let \mathscr P(\mathscr O_n) be the {}^* -subalgebra of {}^* -polynomials in the generators. We show that if \delta is a gauge-invariant derivation mapping \mathscr P(\mathscr O_n) into \mathscr P(\mathscr O_n) , and \delta is approximately …