UNBOUNDED DERIVATIONS OF COMMUTATIVE CSTAR-ALGEBRAS

It is shown that an unbounded *-derivation δ of a unital commutative C*-algebra A is quasi well-behaved if and only if there is a dense open subset U of the spectrum of A such that, for any f in the domain of δ, δ(f) vanishes at any point of U where f attains its norm. An example is given to show th...