\begin{center}
\begin{tikzpicture}
[
  examples
  , x=1cm
  , y=-1cm
  , every node/.style={node distance=1cm and 1cm, on grid}
  , rule_dep/.style={align=center, draw}
  , rule_arrow/.style={<-}
  , rule_arrow_neg/.style={rule_arrow, dashed}
]

%
% normal rules
%
\only<4>{
\node at (0,0) (x) {$\phantom{{A}_{\{s \leftarrow \naf{q}, \naf{r}\}}}\boldsymbol{X}=\{\{\}, \{r\}, \{p, q\}\}$};
\node[below=of x] (aofx) {$\A{\{s \leftarrow \naf{q}, \naf{r}\}}{\boldsymbol{X}}=\{\{s\},\{r\},\{p,q\}\}$};

% line 3
\node[smodel, right=of x.east, xshift=-6mm] (node31) {};
\node[smodel, right=of node31]              (node32) {$r$};
\node[smodel, right=of node32, xshift=2mm]              (node33) {$p$ $q$};

% line 4
\node[smodel, below=of node31] (node41) {$s$}     edge [arrow] (node31);
\node[smodel, below=of node32] (node42) {$r$}     edge [arrow] (node32);
\node[smodel, below=of node33] (node43) {$p$ $q$} edge [arrow] (node33);

\node[rule, right=of node43.east, xshift=-6mm] (rule_seq_4) {$s \leftarrow \naf{q}, \naf{r}$};
}

%
% choices
%
\only<6>{
\node at (0,0) (x) {$\phantom{{A}_{\{\{r\} \leftarrow \naf{p}\}}}\boldsymbol{X}=\{\{\}, \{p, q\}\}\phantom{,\{r\}}$};
\node[below=of x] (aofx) {$\A{\{\{r\} \leftarrow \naf{p}\}}{\boldsymbol{X}}=\{\{\},\{r\},\{p,q\}\}$};

% line 3
\node[smodel, right=of x.east, xshift=0mm] (node31) {};
\node[smodel, right=of node31, xshift=8mm]              (node32) {$p$ $q$};

% line 4
\node[smodel, below left=of node31, xshift=4mm] (node41) {$$}     edge [arrow] (node31);
\node[smodel, below right=of node31, xshift=-4mm] (node42) {$r$}     edge [arrow] (node31);
\node[smodel, below=of node32] (node43) {$p$ $q$} edge [arrow] (node32);

\node[rule, right=of node43.east, xshift=-6mm] (rule_seq_4) {$\{r\} \leftarrow \naf{p}$};
}

%
% constraints
%
\only<8>{
\node at (0,0) (x) {$\phantom{{A}_{\{\phantom{s}\leftarrow r, \naf{p}\}}}\boldsymbol{X}=\{\{s\}, \{r\}, \{p, q\}\}$};
\node[below=of x] (aofx) {$\A{\{\phantom{s}\leftarrow r, \naf{p}\}}{\boldsymbol{X}}=\{\{s\},\{p,q\}\}\phantom{,\{r\}}$};

% line 3
\node[smodel, right=of x.east, xshift=-6mm] (node31) {$s$};
\node[smodel, right=of node31, xshift=2mm]              (node32) {$r$};
\node[smodel, right=of node32, xshift=4mm]              (node33) {$p$ $q$};

% line 4
\node[smodel, below=of node31] (node41) {$s$}     edge [arrow] (node31);
\node[smodel, below=of node33] (node42) {$p$ $q$} edge [arrow] (node33);

\node[rule, right=of node42.east, xshift=-6mm] (rule_seq_4) {$\phantom{s}\leftarrow r, \naf{p}$};
}

\end{tikzpicture}
\end{center}
