Диаграммы в LaTeX

\subsection{Looking up ``s*ng''}
In this case we need to lookup terms with a wildcard in a middle of a term. Hence, we need to permutate it to the form with a trailing wildcard. Process of searching for such permutation is shown in Figure~\ref{fig:perm_sng}.

\begin{figure}[h]
\begin{center}
\begin{tikzpicture}[thick,
                    node distance=2cm,
                    text height=1.5ex,
                    text depth=.25ex]
    \node[format]       (sng) {\texttt{s*ng}};
    \node[format, right of=sng] (sng1) {\texttt{s*ng\$}};
    \node[format, right of=sng1] (sng2){\texttt{*ng\$s}};
    \node[format, right of=sng2] (sng3){\texttt{ng\$s*}};
    
    \path[->] (sng) edge (sng1);
    \path[->] (sng1) edge (sng2);    
    \path[->] (sng2) edge (sng3);        
    \path[->, draw] (sng1) -- ++(0,1) -- ++(3,0) -- (sng3);
\end{tikzpicture}
\end{center}
\caption{Permutations for wildcard query \texttt{s*ng}}\label{fig:perm_sng}
\end{figure}