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<a NAME="E1:22_1_1"/>
0 <a href="hidden.html#R2">in</a> <span class="p1"><a href="tarski.html#K1">{</a><span class="default">0</span><a href="tarski.html#K1">}</a></span>
 
<b>by </b><i><a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/>
<b>then reconsider </b><font color="Maroon">f</font> = <span class="p1"><a href="tarski.html#K1">{</a><span class="default"><span class="p2"><a href="tarski.html#K4">[</a><span class="default">0,0</span><a href="tarski.html#K4">]</a></span></span><a href="tarski.html#K1">}</a></span> as  non <a href="xboole_0.html#V1">empty</a>  <a href="relset_1.html#M2">Relation</a> of <span class="p1"><a href="tarski.html#K1">{</a><span class="default">0</span><a href="tarski.html#K1">}</a></span>,<span class="p1"><a href="tarski.html#K1">{</a><span class="default">0</span><a href="tarski.html#K1">}</a></span> <b>by </b><i><a class="ref" href="relset_1.html#T8">RELSET_1:8</a></i>;<br/>
<b>take </b><font color="Maroon">PTN1</font> =  <a href="petri.html#G1" target="_self">PT_net_Str</a>(# <span class="p1"><a href="tarski.html#K1">{</a><span class="default">0</span><a href="tarski.html#K1">}</a></span>,<span class="p1"><a href="tarski.html#K1">{</a><span class="default">0</span><a href="tarski.html#K1">}</a></span>,<font color="Maroon">f</font>,<font color="Maroon">f</font> #);<br/>

<a NAME="E3:22_1_1"/>
<span class="p1"><a href="tarski.html#K1">{</a><span class="default">0</span><a href="tarski.html#K1">}</a></span> <a href="tarski.html#R1">c=</a> the <a href="petri.html#U1" target="_self">Places</a> of <font color="Maroon">PTN1</font>
 
;<br/>
<b>then reconsider </b><font color="Maroon">S</font> = <span class="p1"><a href="tarski.html#K1">{</a><span class="default">0</span><a href="tarski.html#K1">}</a></span> as   <a href="subset_1.html#NM2">Subset</a> of the <a href="petri.html#U1" target="_self">Places</a> of <font color="Maroon">PTN1</font> ;<br/>
<b>take </b>
<font color="Maroon">S</font>
; <i><font color="Red">:: according to </font></i><a class="ref" href="petri.html#D6" target="_self">PETRI:def 6</a><br/>

<b>reconsider </b><font color="Maroon">s</font> = 0 as   <a href="petri.html#NM2">place</a> of <font color="Maroon">PTN1</font> <b>by </b><i><a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/>
<b>reconsider </b><font color="Maroon">t</font> = 0 as   <a href="petri.html#NM4">transition</a> of <font color="Maroon">PTN1</font> <b>by </b><i><a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/>
<b>reconsider </b><font color="Maroon">stf</font> = <span class="p1"><a href="tarski.html#K4">[</a><span class="default">0,0</span><a href="tarski.html#K4">]</a></span> as   <a href="petri.html#NM6">S-T_arc</a> of <font color="Maroon">PTN1</font> <b>by </b><i><a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/>
<b>reconsider </b><font color="Maroon">tsf</font> = <span class="p1"><a href="tarski.html#K4">[</a><span class="default">0,0</span><a href="tarski.html#K4">]</a></span> as   <a href="petri.html#NM7">T-S_arc</a> of <font color="Maroon">PTN1</font> <b>by </b><i><a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/>
<a NAME="E9:22_1_1"/>
( <font color="Maroon">tsf</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="domain_1.html#K1">[</a><span class="default"><font color="Maroon">t</font>,<font color="Maroon">s</font></span><a href="domain_1.html#K1">]</a></span> &amp; <font color="Maroon">s</font> <a href="hidden.html#R2">in</a> <font color="Maroon">S</font> )
 
;<br/>
<a NAME="E10:22_1_1"/><b>then </b>
<font color="Maroon">t</font> <a href="hidden.html#R2">in</a>  <a href="petri.html#K5" target="_self">*'</a> <font color="Maroon">S</font>
 
;<br/>
<a NAME="E11:22_1_1"/><b>then </b>
<span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">t</font></span><a href="domain_1.html#K6">}</a></span> <a href="tarski.html#R1">c=</a>  <a href="petri.html#K5" target="_self">*'</a> <font color="Maroon">S</font>
 
<b>by </b><i><a class="ref" href="zfmisc_1.html#T37">ZFMISC_1:37</a></i>;<br/>
<a NAME="E12:22_1_1"/><b>then </b><i><font color="Green">E18</font></i>: 
<span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">t</font></span><a href="domain_1.html#K6">}</a></span> <a href="hidden.html#R1">=</a>  <a href="petri.html#K5" target="_self">*'</a> <font color="Maroon">S</font>
 
<b>by </b><i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a></i>;<br/>
<a NAME="E13:22_1_1"/>
( <font color="Maroon">stf</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="domain_1.html#K1">[</a><span class="default"><font color="Maroon">s</font>,<font color="Maroon">t</font></span><a href="domain_1.html#K1">]</a></span> &amp; <font color="Maroon">s</font> <a href="hidden.html#R2">in</a> <font color="Maroon">S</font> )
 
;<br/>
<a NAME="E14:22_1_1"/><b>then </b>
<font color="Maroon">t</font> <a href="hidden.html#R2">in</a> <font color="Maroon">S</font> <a href="petri.html#K6" target="_self">*'</a> 
 
;<br/>
<b>hence </b><a NAME="E15:22_1_1"/>
 <a href="petri.html#K5" target="_self">*'</a> <font color="Maroon">S</font> is   <a href="subset_1.html#NM2">Subset</a> of <span class="p1">(<span class="default"><font color="Maroon">S</font> <a href="petri.html#K6" target="_self">*'</a> </span>)</span>
 <b>by </b><i>, <a class="ref" href="zfmisc_1.html#T37">ZFMISC_1:37</a></i>; <i><font color="Red">:: according to </font></i><a class="ref" href="petri.html#D5" target="_self">PETRI:def 5</a><br/>


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