Suppose A is a (possibly unbounded) linear operator on a Banach space. We show that the following are equivalent. (1) A is well-bounded on [0,∞). (2) -A generates a strongly continuous semigroup ${e^{-sA}}_{s\le 0}$ such that ${(1/s^2)e^{-sA}}_{s>0}$ is the Laplace transform of a Lipschitz continuous family of operators that vanishes at 0. (3) -A generates a strongly continuous differentiable semigroup ${e^{-sA}}_{s\ge 0}$ and ∃ M < ∞ such that $\parallel H_n\left(s\right)\parallel \equiv \parallel ({\sum }_{k=0}^n\left(s^k{A}^k\right)/k!)e^{-sA}\parallel \le M$, ∀s > 0, n ∈ ℕ ∪ 0. (4) -A generates a strongly continuous holomorphic semigroup ${e^{-zA}}_{Re\left(z\right)>0}$ that is O(|z|) in all...

An increasing sequence ${\left(n_k\right)}_{k\ge 0}$ of positive integers is said to be a Jamison sequence if for every separable complex Banach space X and every T ∈ ℬ(X) which is partially power-bounded with respect to ${\left(n_k\right)}_{k\ge 0}$, the set ${\sigma }_p\left(T\right)\cap$ is at most countable. We prove that for every separable infinite-dimensional complex Banach space X which admits an unconditional Schauder decomposition, and for any sequence ${\left(n_k\right)}_{k\ge 0}$ which is not a Jamison sequence, there exists T ∈ ℬ(X) which is partially power-bounded with respect to ${\left(n_k\right)}_{k\ge 0}$ and has the...