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<a NAME="E1:71_1_1"/><i><font color="Green">E17</font></i>: 
( <font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a>  <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  implies <font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a>  <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  )
 
;<br/>
<b>set </b><font color="Maroon">f</font> =  <a href="partfun1.html#K6">id</a> <span class="p1">(<span class="default"><font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a> </span>)</span>;<br/>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="71_1_1_1"><b>now </b></a><div class="add"><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>assume </b><a NAME="E1:71_1_1_1"/><i><font color="Green">E18</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> <font color="Maroon">T</font> <a href="coh_sp.html#K19" target="_self">`1</a> 
 ;<br/><a NAME="E2:71_1_1_1"/><b>then </b>
( <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a>  &amp; <font color="Maroon">y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a>  )
 <b>by </b><i><a class="ref" href="zfmisc_1.html#T106">ZFMISC_1:106</a></i>;<br/><a NAME="E3:71_1_1_1"/><b>then </b>
( <span class="p1">(<span class="default"><a href="partfun1.html#K6">id</a> <span class="p2">(<span class="default"><font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a> </span>)</span></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">x</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x</font> &amp; <span class="p1">(<span class="default"><a href="partfun1.html#K6">id</a> <span class="p2">(<span class="default"><font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a> </span>)</span></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">y</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y</font> )
 <b>by </b><i><a class="ref" href="funct_1.html#T35">FUNCT_1:35</a></i>;<br/><b>hence </b><a NAME="E4:71_1_1_1"/>
<span class="p1"><a href="tarski.html#K4">[</a><span class="default"><span class="p2">(<span class="default"><span class="p3">(<span class="default"><a href="partfun1.html#K6">id</a> <span class="p4">(<span class="default"><font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a> </span>)</span></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">x</font></span>)</span>,<span class="p2">(<span class="default"><span class="p3">(<span class="default"><a href="partfun1.html#K6">id</a> <span class="p4">(<span class="default"><font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a> </span>)</span></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">y</font></span>)</span></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <font color="Maroon">T</font> <a href="coh_sp.html#K19" target="_self">`1</a> 
 <b>by </b><i><a class="ref" href="coh_sp.html#T7" target="_self">Th7</a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E3:71_1_1"/>
<span class="p1"><a href="tarski.html#K4">[</a><span class="default"><span class="p2"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">T</font>,<font color="Maroon">T</font></span><a href="tarski.html#K4">]</a></span>,<span class="p2">(<span class="default"><a href="partfun1.html#K6">id</a> <span class="p3">(<span class="default"><font color="Maroon">T</font> <a href="coh_sp.html#K18" target="_self">`2</a> </span>)</span></span>)</span></span><a href="tarski.html#K4">]</a></span> is    <a href="subset_1.html#M1">Element</a> of  <a href="coh_sp.html#K21" target="_self">MapsT</a> <font color="Maroon">X</font>
 <b>by </b><i>, </i>;<br/>


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