deletions | additions
diff --git a/section_Convergence_label_sec_convergence__.tex b/section_Convergence_label_sec_convergence__.tex
index d6d8964..45ad524 100644
--- a/section_Convergence_label_sec_convergence__.tex
+++ b/section_Convergence_label_sec_convergence__.tex
...
This brings us back to convergence result for general (not necessarily Boolean) DeGroot processes. Indeed, for functional and serial influence graphs, a closed connected component is aperiodic if and only if its cycle is of length $1$.
\begin{lemma}\label{lemma:influence}
Let
$\G=(G_{p_1},\dots,G_{p_m})$ $\G$ be an influence profile. Then the following are equivalent:
\begin{itemize}
\item[] The BDP converges for any opinion profile $\O$ on $\G$
\item[] For all
$j\in \{1,\ldots,m\}$, $G_{p_j}$ $p\in \Atoms$, $G_{p}$ contains no cycle of length $\geq 2$.
\item[] For all
$j\in \{1,\ldots,m\}$, $p\in \Atoms $, all closed connected components of
$G_{p_j}$ $G_{p}$ are aperiodic.
\end{itemize}
\end{lemma}
\begin{proof}
Let
$j\in\{1,\dots,m\}$ $p\in\Atoms$ and assume that
$G_{p_j}$ $G_{p}$ contains no cycle of length $\geq 2$ and has diameter $k$. Let
$C_{p_j}$ $C_{p}$ be a connected component of
$G_{p_j}$. $G_{p}$. By \ref{fact:uniquecycle},
$C_{p_j}$ $C_{p}$ contains a unique cycle, which, by assumption, is of length $1$. Hence,
$C_{p_j}$ $C_{p}$ is aperiodic. Let $i$ be the node in the cycle. The opinion of $i$ will spread to all nodes in
$C_{p_j}$ $C_{p}$ after at most $k$ steps. Therefore, all BDPs on $G$ will converge after at most $l$ steps, where $l$ is the maximum within the set of diameters of
$G_{p_j}$ $G_{p}$ for all
$j\in \{1,\ldots,m\}$. $p\in\Atoms$.
Assume that for some
$j\in\{1,\dots,m\}$, $p\in\Atoms$, a connected component
$C_{p_j}$ $C_{p}$ of
$G_{p_j}$ $G_{p}$ contains a cycle of length $k\geq 2$. By \ref{fact:uniquecycle}, this cycle is unique, and therefore the greatest common divisor of the cycles lengths of
$C_{p_j}$ $C_{p}$ is $k$, so
$C_{p_j}$ $C_{p}$ is not aperiodic.
Let $S$ be the set of nodes in the cycle.
Let $\O$ be such that for some $i,j\in S$ with distance $d$ from $i$ to $j$,
$O_i{p_j}\neq O_j{p_j}$. $O_i{p}\neq O_j{p}$. Then
$O_i{p_j}$ $O_i{p}$ will not converge, but enter a loop of size $k$: for all $x\in\mathbb{N}$, $O^{x\times
k}_i{p_j}=\neq k}_i{p}=\neq O^{(x\times
k)+d}_i{p_j}$. k)+d}_i{p}$.
\end{proof}
Note that that one direction of the above result also follows both from the DeGroot convergence result stated earlier (since graphs with only cycles of length $1$ are trivially aperiodic) and from the propositional opinion diffusion sufficient condition above (since the unanimity rule is trivially monotonic).