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<b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">y</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">N</font> be   <a href="net_1.html#NM1">Pnet</a>;<br/>





<b>assume </b><a NAME="E1:12"/><i><font color="Green">E13</font></i>: 
( <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">x</font>,<font color="Maroon">y</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> the <a href="net_1.html#U3" target="_self">Flow</a> of <font color="Maroon">N</font> &amp; <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> the <a href="net_1.html#U2" target="_self">Transitions</a> of <font color="Maroon">N</font> )
 ;<br/>

<a NAME="E2:12"/>
the <a href="net_1.html#U3" target="_self">Flow</a> of <font color="Maroon">N</font> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default">the <a href="net_1.html#U1" target="_self">Places</a> of <font color="Maroon">N</font>,the <a href="net_1.html#U2" target="_self">Transitions</a> of <font color="Maroon">N</font></span><a href="zfmisc_1.html#K2">:]</a></span> <a href="xboole_0.html#K2">\/</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default">the <a href="net_1.html#U2" target="_self">Transitions</a> of <font color="Maroon">N</font>,the <a href="net_1.html#U1" target="_self">Places</a> of <font color="Maroon">N</font></span><a href="zfmisc_1.html#K2">:]</a></span>
 
<b>by </b><i/>;<br/>
<a NAME="E3:12"/><b>then </b><i><font color="Green">E17</font></i>: 
( <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">x</font>,<font color="Maroon">y</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default">the <a href="net_1.html#U1" target="_self">Places</a> of <font color="Maroon">N</font>,the <a href="net_1.html#U2" target="_self">Transitions</a> of <font color="Maroon">N</font></span><a href="zfmisc_1.html#K2">:]</a></span> or <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">x</font>,<font color="Maroon">y</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default">the <a href="net_1.html#U2" target="_self">Transitions</a> of <font color="Maroon">N</font>,the <a href="net_1.html#U1" target="_self">Places</a> of <font color="Maroon">N</font></span><a href="zfmisc_1.html#K2">:]</a></span> )
 
<b>by </b><i>, <a class="ref" href="xboole_0.html#D2">XBOOLE_0:def 2</a></i>;<br/>
<a NAME="E4:12"/>
not <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> the <a href="net_1.html#U1" target="_self">Places</a> of <font color="Maroon">N</font>
 
<b>by </b><i>, </i>;<br/>
<b>hence </b><a NAME="E5:12"/>
<font color="Maroon">y</font> <a href="hidden.html#R2">in</a> the <a href="net_1.html#U1" target="_self">Places</a> of <font color="Maroon">N</font>
 <b>by </b><i><a class="ref" href="net_1.html#D1" target="_self">Def1</a>, <a class="ref" href="zfmisc_1.html#T106">ZFMISC_1:106</a></i>;<br/>


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