\item $\bordermatrix{
i\setminus s& P_1 & P_2 & P_3 & P_4\cr
P_1 & 1 & 0 & 0 & 0\cr
- P_2 & 0 & 1 & \cr
- P_3 & 0 & 0 & 1\cr
+ P_2 & 0 & 1 & 0 & 0\cr
+ P_3 & 0 & 0 & 1 & 0\cr
P_4 & 0 & 0 & 1 & 1\cr
}$
\item
- $P_1=\xymatrix{
+ $P_1=\xymatrix@C=1pc@R=1pc{
\ar[dr]&\\
- & s_0\ar[d]^a\\
- & s_1\ar[d]^b\\
- & s_2\ar[d]^c\\
- & s_3\\
+ & *+[o][F-]{s_0}\ar[d]^a\\
+ & *+[o][F-]{s_1}\ar[d]^b\\
+ & *+[o][F-]{s_2}\ar[d]^c\\
+ & *+[o][F-]{s_3}\\
}$
- $P_2=\xymatrix{
+ $P_2=\xymatrix@C=1pc@R=1pc{
\ar[dr]&\\
- & s_0\ar[d]^a\\
- & s_1\ar[d]^b\\
- & s_2\ar[dl]^c\ar[dr]^d\\
- s_3 & & s_4\\
+ & *+[o][F-]{s_0}\ar[d]^a\\
+ & *+[o][F-]{s_1}\ar[d]^b\\
+ & *+[o][F-]{s_2}\ar[dl]_c\ar[dr]^d\\
+ *+[o][F-]{s_3} & & *+[o][F-]{s_4}\\
}$
- $P_3=\xymatrix{
- \ar[dr] &\\
- & s_0\ar[d]^a\\
- & s_1\ar[dl]^b\ar[dr]^b\\
- s_2\ar[d]^c & & s_3\ar[d]^d\\
- s_4 & & s_5\\
+ $P_3=\xymatrix@C=1pc@R=1pc{
+ \ar[dr] &\\
+ & *+[o][F-]{s_0}\ar[d]^a\\
+ & *+[o][F-]{s_1}\ar[dl]_b\ar[dr]^b\\
+ *+[o][F-]{s_2}\ar[d]^c & & *+[o][F-]{s_3}\ar[d]^d\\
+ *+[o][F-]{s_4} & & *+[o][F-]{s_5}\\
}$
- $P_4=\xymatrix{
- \ar[dr] &\\
- & s_0\ar[dl]^a\ar[dr]^a\\
- s_2\ar[d]^b & & s_3\ar[d]^b\\
- s_4\ar[d]^c & & s_5\ar[d]^d\\
- s_6 & & s_7
+ $P_4=\xymatrix@C=1pc@R=1pc{
+ \ar[dr] &\\
+ & *+[o][F-]{s_0}\ar[dl]_a\ar[dr]^a\\
+ *+[o][F-]{s_2}\ar[d]^b & & *+[o][F-]{s_3}\ar[d]^b\\
+ *+[o][F-]{s_4}\ar[d]^c & & *+[o][F-]{s_5}\ar[d]^d\\
+ *+[o][F-]{s_6} & & *+[o][F-]{s_7}
}$
\end{enumerate}
\subsection{Testing equivalences}
+\begin{enumerate}[a)]
+ \item
+ \begin{align*}
+ \sigma\in traces(p)\leftrightarrow
+ p\text{ \bf after }\sigma\text{ \bf refuses }\emptyset\\
+ \sigma\in traces(p)\leftrightarrow
+ \exists p':p\overset{\sigma}{\Rightarrow}p'\text{ and }\forall a\in
+ \emptyset:p'\cancel{\overset{a}{\rightarrow}} & & 2.\\
+ \sigma\in traces(p)\leftrightarrow
+ \exists p':p\overset{\sigma}{\Rightarrow}p'\\
+ \sigma\in \{\sigma\in L^*|p\overset{\sigma}{\Rightarrow}\}\leftrightarrow
+ \exists p':p\overset{\sigma}{\Rightarrow}p'& & \square\\
+ \end{align*}
+ \item
+ \begin{align*}
+ p\text{ \bf after }\sigma\text{ \bf refuses } A\leftrightarrow
+ \sigma\cdot A\in Ftraces(p)\\
+ \exists p':p\overset{\sigma}{\Rightarrow}p'\text{ and }\forall a\in
+ A:p'\cancel{\overset{a}{\rightarrow}} \leftrightarrow
+ \sigma\cdot A\in Ftraces(p) & & 2.\\
+ \exists p':p\overset{\sigma}{\Rightarrow}p'\text{ and }\forall a\in
+ A:p'\cancel{\overset{a}{\rightarrow}} \leftrightarrow
+ \sigma\cdot A\in \{\psi\in(L\cup
+ \mathcal{P}(L))^*|p\overset{\sigma}{\Rightarrow}\} & & 4.\\
+ \end{align*}
+ \item
+ \begin{align*}
+ \end{align*}
+ \item
+ \begin{align*}
+ \end{align*}
+\end{enumerate}
+
\subsection{Testing equivalences}
\subsection{Testing equivalences}