如何在标题中输入多行公式? LaTeX

http://*.com/questions/2716227/adding-an-equation-or-formula-to-a-figure-caption-in-latex

\begin{figure}
\begin{center}
    ...
    \captionsetup{singlelinecheck=off}
    \caption[.]{
    \begin{displaymath}
        assoc\_meaning(\lambda x_{SBJ}. followed(x,y) \&actor(x) \nonumber \&actor(y),\lambda x_{SBJ}. maintained(x,\nonumber <(dist\_from(y),1))
    \end{displaymath}}
\end{center}
\end{figure}