Stable family of semigroup generators
= Stable family of semigroup generators
A time-indexed family $A(t)$ is stable with constants $M,\omega$ when products of its frozen semigroups obey
$$
\left\|e^{s_nA(t_n)}\cdots e^{s_1A(t_1)}\right\|
\leq Me^{\omega(s_1+\cdots+s_n)}
$$
for all nonnegative $s_j$. This condition controls products uniformly as the number of time slices grows.