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1.8 KiB

$$f = (r \land \lnot p) \lor (r \land \lnot p) \lor (s \land \lnot r) \lor (\lnot s \land r)\lor (r \land q),$$
\begin{cofactors}
$f_{p}$ \= $= \lnot r \lor(s \land \lnot r) \lor (\lnot s \land r) \lor (r \land q)$ \\
\>$f_{pq}$ \= $= \true$\\
\>$f_{p\lnot q}$ \= $= r \lor (s \land \lnot r) \lor (\lnot s \land r)$\\
\>\>$f_{p\lnot qr}$ \= $= \true$\\
\>\>$f_{p\lnot q\lnot r}$ \= $= s$\\
\>\>\>$f_{p\lnot q\lnot rs}$ \= $= \true$\\
\>\>\>$f_{p\lnot q\lnot r\lnot s}$ \= $= \false$\\
$f_{\lnot p}$ \= $= r \lor(s \land \lnot r) \lor (\lnot s \land r) \lor (r \land q)$ \\
\>$f_{\lnot pq}$ \= $= r \lor(s \land \lnot r) \lor (\lnot s \land r)$ \\
\>$f_{\lnot p\lnot q}$ \= $= r \lor(s \land \lnot r) \lor (\lnot s \land r)$ \\
\>\>$\Rightarrow q$ does not have an influence on the formula. These cofactors can be skipped.\\
\>$f_{\lnot pr}$ \= $= \true$ \\
\>$f_{\lnot p\lnot r}$ \= $= s = f_{p\lnot q\lnot r}$ \\
\end{cofactors}
The final ROBDD:\\
\begin{center}
\begin{bdd}[4em]
\node[func node] (f) {$f$};
\node[cofactor] (p1) [below of=f] {$q$};
\node[cofactor] (q1) [below left of=p1] {$q$};
\node[cofactor] (r1) [below right of=p1] {$r$};
\node[cofactor] (r2) [below right of=q1,yshift=-0.8em,xshift=-1.5em] {$r$};
\node[phantom] (q1L) [below left of=q1] {};
\node[phantom] (r1L) [below left of=r1] {};
\node[cofactor] (s1) [below left of=r2] {$s$};
\node[phantom] (r2L) [below left of=r2] {};
\node[phantom] (r2R) [below right of=r2] {};
\node[phantom] (s2L) [below left of=s1] {};
\node[phantom] (s2R) [below right of=s1] {};
\funcEdge{f}{p1}
\thenEdge{p1}{q1}
\elseEdge{p1}{r1}
\thenEdge{q1}{q1L}
\negatedEdge{q1}{r2}
\thenEdge{r2}{s1}
\negatedEdge{r2}{r2R}
\thenEdge{r1}{r1L}
\elseEdge[bend left]{r1}{s1}
\thenEdge{s1}{s2L}
\negatedEdge{s1}{s2R}
\end{bdd}
\end{center}