1 \begin{block}{Definition: Chaotic function [4]$^4$}
2 Let $(\mathcal{X}; d)$ be a metric space.
3 A function $f: \mathcal{X} \rightarrow \mathcal{X}$ is chaotic on $\mathcal{X}$ if:
5 \item $f$: topologically transitive (\textit{i.e.}, indecomposability of the system)\\
6 (for any pair of open sets $U,V \subset \mathcal{X}$, $\exists k > 0 .
7 f^k (U) \cap V \neq \emptyset$)
9 \onslide<2>{\alert<2>{Addressed property: preimage resistance}}.
10 \item $f$ is regular (\textit{i.e.}, fundamentally different points coexist)\\
11 (the set of periodic points is dense in $\mathcal{X}$).
12 \item $f$: sensitive dependent on initial conditions (SDIC)\\
14 \exists \delta > 0 . \forall x \in \mathcal{X}
16 \forall V \textrm{ neighborhood of $x$}.
17 \exists y \in V \textrm{ and }
19 d(f^n(x); f^n(y))> \delta
21 \onslide<2>{\alert<2>{Addressed properties: avalanche effect}}.
24 \footnote{\bibentry{devaney}}