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<b>let </b><font color="Maroon">C1</font> be   <a href="coh_sp.html#NM1">Coherence_Space</a>, <font color="Maroon">C2</font> be   <a href="coh_sp.html#NM1">Coherence_Space</a>;<br/><b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ;<br/>



<div><b>hereby </b>
<div class="add"><b>assume </b><a NAME="E1:157_1"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C1</font> <a href="cohsp_1.html#K17" target="_self">[*]</a> <font color="Maroon">C2</font>
 ;<br/><b>then consider </b><font color="Maroon">y</font> being    <a href="hidden.html#M1">set</a> <b> such that </b><br/><a NAME="E3:157_1"/><i><font color="Green">E26</font></i>: 
( <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">y</font> &amp; <font color="Maroon">y</font> <a href="hidden.html#R2">in</a> <span class="p1">{<span class="default"> <span class="p2">(<span class="default"><a href="zfmisc_1.html#K1">bool</a> <span class="p3"><a href="zfmisc_1.html#K2">[:</a><span class="default"><font color="Olive">a</font>,<font color="Olive">b</font></span><a href="zfmisc_1.html#K2">:]</a></span></span>)</span> where <font color="Olive">a</font> is    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">C1</font>, <font color="Olive">b</font> is    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">C2</font> : verum </span>}</span>  )
 <b>by </b><i><a class="ref" href="tarski.html#D4">TARSKI:def 4</a></i>;<br/><b>consider </b><font color="Maroon">a</font> being    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">C1</font>, <font color="Maroon">b</font> being    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">C2</font><b> such that </b><br/><a NAME="E5:157_1"/><i><font color="Green">E27</font></i>: 
<font color="Maroon">y</font> <a href="hidden.html#R1">=</a>  <a href="zfmisc_1.html#K1">bool</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font></span><a href="zfmisc_1.html#K2">:]</a></span>
 <b>by </b><i/>;<br/><b>take </b><font color="Maroon">a</font> = <font color="Maroon">a</font>;<br/><b>take </b><font color="Maroon">b</font> = <font color="Maroon">b</font>;<br/><b>thus </b><a NAME="E6:157_1"/>
<font color="Maroon">x</font> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font></span><a href="zfmisc_1.html#K2">:]</a></span>
 <b>by </b><i>, </i>;<br/></div>
<b>end;</b></div>

<b>given </b><font color="Maroon">a'</font> being    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">C1</font>, <font color="Maroon">b'</font> being    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">C2</font><b> such that </b><a NAME="E2:157"/><i><font color="Green">E36</font></i>: 
<font color="Maroon">x</font> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><font color="Maroon">a'</font>,<font color="Maroon">b'</font></span><a href="zfmisc_1.html#K2">:]</a></span>
 ;<br/>

<a NAME="E3:157"/>
( <font color="Maroon">x</font> <a href="hidden.html#R2">in</a>  <a href="zfmisc_1.html#K1">bool</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><font color="Maroon">a'</font>,<font color="Maroon">b'</font></span><a href="zfmisc_1.html#K2">:]</a></span> &amp;  <a href="zfmisc_1.html#K1">bool</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><font color="Maroon">a'</font>,<font color="Maroon">b'</font></span><a href="zfmisc_1.html#K2">:]</a></span> <a href="hidden.html#R2">in</a> <span class="p1">{<span class="default"> <span class="p2">(<span class="default"><a href="zfmisc_1.html#K1">bool</a> <span class="p3"><a href="zfmisc_1.html#K2">[:</a><span class="default"><font color="Olive">a</font>,<font color="Olive">b</font></span><a href="zfmisc_1.html#K2">:]</a></span></span>)</span> where <font color="Olive">a</font> is    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">C1</font>, <font color="Olive">b</font> is    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">C2</font> : verum </span>}</span>  )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E4:157"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C1</font> <a href="cohsp_1.html#K17" target="_self">[*]</a> <font color="Maroon">C2</font>
 <b>by </b><i><a class="ref" href="tarski.html#D4">TARSKI:def 4</a></i>;<br/>


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