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<b>consider </b><font color="Maroon">c<sub>2</sub></font> being    <a href="pre_topc.html#L1">TopStruct</a> ;<br/>
<b>take </b>
<font color="Maroon">c<sub>1</sub></font> <a href="pre_circ.html#K2">--&gt;</a> <font color="Maroon">c<sub>2</sub></font>
;<br/>

<b>let </b><font color="Maroon">c<sub>3</sub></font> be    <a href="hidden.html#M1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="pencil_1.html#D13" target="_self">PENCIL_1:def 13</a><br/>

<a NAME="E2:21_1_1"/><i><font color="Green">E22</font></i>: 
 <a href="relat_1.html#K2">rng</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>1</sub></font> <a href="pre_circ.html#K2">--&gt;</a> <font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="tarski.html#K1">{</a><span class="default"><font color="Maroon">c<sub>2</sub></font></span><a href="tarski.html#K1">}</a></span>
 
<b>by </b><i><a class="ref" href="funcop_1.html#T19">FUNCOP_1:19</a></i>;<br/>
<b>assume </b><a NAME="E3:21_1_1"/>
<font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R2">in</a>  <a href="relat_1.html#K2">rng</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>1</sub></font> <a href="pre_circ.html#K2">--&gt;</a> <font color="Maroon">c<sub>2</sub></font></span>)</span>
 ;<br/>

<b>hence </b><a NAME="E4:21_1_1"/>
<font color="Maroon">c<sub>3</sub></font> is    <a href="pre_topc.html#L1">TopStruct</a> 
 <b>by </b><i><a class="txt" href="pencil_1.html#E2:21_1_1"><i><font color="Green">E22</font></i></a>, <a class="ref" href="tarski.html#D1">TARSKI:def 1</a></i>;<br/>


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