  This paper presents the software Partial Pole Placement via Delay Action, or
P3$\delta$ for short. P3$\delta$ is a Python software with a friendly user
interface for the design of parametric stabilizing feedback laws with
time-delays, thanks to two properties of the distribution of quasipolynomials'
zeros, called multiplicity-induced-dominancy and coexisting real
roots-induced-dominancy. After recalling recent theoretical results on these
properties and their use for the feedback stabilization of control systems
operating under time delays, the paper presents the main features of the
current version of P3$\delta$. We detail, in particular, the assignable
admissible region (the set of allowable dominant roots and the corresponding
delay), which helps the user in the choice of input information, allowing a
reliable stabilizing delayed feedback. We also present the newly set online
version of P3$\delta$.

Optimization and Control