thousand) per day within the next 100 days, and the immune population should eventually exceed 6 million after 40 to 60 days” (we assume that the unit is million in this paper unless otherwise indicated).

We define the set of states that satisfy the atomic proposition $\pi$ as $\mathcal{O}(\pi)\subset \mathcal{X}$. We denote the distance from $x$ to a set $D\subseteq\mathcal{X}$ as **dist**$_d(x,D)\triangleq$inf$\{d(x, x')\mid x'\in cl(D)\}$, where $d$ is a metric on $\mathcal{X}$ and $cl(D)$ denotes the closure of the set $D$. In this paper, we use the metric $d(x,x')={\left\lVertx-x'\right\rVert}$, where $\left\Vert\cdot\right\Vert $ denotes the 2-norm. We denote the depth of $x$ in $D$ as **depth**$_d(x,D)\triangleq$ **dist**$_d(x,\mathcal{X}\setminus D)$. We define the signed distance from $x$ to $D$ as $\textbf{Dist}_d(x,D)\triangleq-\textbf{dist}_d(x,D)$, if $x$ $\not\in D$; and $\textbf{Dist}_d(x,D)\triangleq\textbf{depth}_d(x,D)$, if $x$ $\in D$. The Boolean semantics of MTL can be found in [@FAINEKOScontinous], with the slight variation that we only evaluate the satisfaction of a trajectory with respect to an MTL formula at discrete-time instants $t[k]~(k\in\mathcal{I})$. The robustness degree of a trajectory $\xi$ with respect to an MTL formula $\varphi$ at time index $k$, denoted as $\left[\left[\varphi\right]\right](\xi, k)$, is defined recursively as follows: $$\begin{split}
\left[\left[\top\right]\right](\xi, k) :=& +\infty,\\
\left[\left[ \pi\right]\right](\xi, k)  :=&\textbf{Dist$_d(x[k],\mathcal{O}(\pi))$},\\
\left[\left[ \neg\varphi\right]\right](\xi, k)  