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<b>let </b><font color="Maroon">C</font> be   <a href="altcat_1.html#NM4">category</a>;<br/><b>let </b><font color="Maroon">D</font> be  non <a href="struct_0.html#V3">empty</a> <a href="altcat_2.html#NM2">subcategory</a> of <font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">o</font> be   <a href="altcat_1.html#NM1">object</a> of <font color="Maroon">D</font>;<br/><b>let </b><font color="Maroon">o'</font> be   <a href="altcat_1.html#NM1">object</a> of <font color="Maroon">C</font>;<br/>







<b>assume </b><a NAME="E1:76"/><i><font color="Green">E16</font></i>: 
<font color="Maroon">o</font> <a href="hidden.html#R1">=</a> <font color="Maroon">o'</font>
 ;<br/>

<a NAME="E2:76"/><b>then </b><i><font color="Green">E17</font></i>: 
 <a href="altcat_1.html#K8">idm</a> <font color="Maroon">o'</font> <a href="hidden.html#R2">in</a> <span class="p1"><a href="altcat_1.html#K1">&lt;^</a><span class="default"><font color="Maroon">o</font>,<font color="Maroon">o</font></span><a href="altcat_1.html#K1">^&gt;</a></span>
 
<b>by </b><i/>;<br/>
<b>reconsider </b><font color="Maroon">m</font> =  <a href="altcat_1.html#K8">idm</a> <font color="Maroon">o'</font> as   <a href="altcat_1.html#NM2">Morphism</a> of <font color="Maroon">o</font>,<font color="Maroon">o</font> <b>by </b><i>, </i>;<br/>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="76_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">p</font> be   <a href="altcat_1.html#NM1">object</a> of <font color="Maroon">D</font>;<br/><b>assume </b><a NAME="E1:76_1"/><i><font color="Green">E20</font></i>: 
<span class="p1"><a href="altcat_1.html#K1">&lt;^</a><span class="default"><font color="Maroon">o</font>,<font color="Maroon">p</font></span><a href="altcat_1.html#K1">^&gt;</a></span> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 ;<br/><b>let </b><font color="Maroon">a</font> be   <a href="altcat_1.html#NM2">Morphism</a> of <font color="Maroon">o</font>,<font color="Maroon">p</font>;<br/><b>reconsider </b><font color="Maroon">p'</font> = <font color="Maroon">p</font> as   <a href="altcat_1.html#NM1">object</a> of <font color="Maroon">C</font> <b>by </b><i/>;<br/><a NAME="E3:76_1"/>
<span class="p1"><a href="altcat_1.html#K1">&lt;^</a><span class="default"><font color="Maroon">o</font>,<font color="Maroon">p</font></span><a href="altcat_1.html#K1">^&gt;</a></span> <a href="tarski.html#R1">c=</a> <span class="p1"><a href="altcat_1.html#K1">&lt;^</a><span class="default"><font color="Maroon">o'</font>,<font color="Maroon">p'</font></span><a href="altcat_1.html#K1">^&gt;</a></span>
 <b>by </b><i>, </i>;<br/><a NAME="E4:76_1"/><b>then </b><i><font color="Green">E21</font></i>: 
<span class="p1"><a href="altcat_1.html#K1">&lt;^</a><span class="default"><font color="Maroon">o'</font>,<font color="Maroon">p'</font></span><a href="altcat_1.html#K1">^&gt;</a></span> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 <b>by </b><i>, <a class="ref" href="xboole_1.html#T3">XBOOLE_1:3</a></i>;<br/><b>reconsider </b><font color="Maroon">n</font> = <font color="Maroon">a</font> as   <a href="altcat_1.html#NM2">Morphism</a> of <font color="Maroon">o'</font>,<font color="Maroon">p'</font> <b>by </b><i>, , </i>;<br/><b>thus </b><font color="Maroon">a</font> <a href="altcat_1.html#K5">*</a> <font color="Maroon">m</font> = 
<font color="Maroon">n</font> <a href="altcat_1.html#K5">*</a> <span class="p1">(<span class="default"><a href="altcat_1.html#K8">idm</a> <font color="Maroon">o'</font></span>)</span>
<b>by </b><i>, , , </i>
<br/>.= 
<font color="Maroon">a</font>
<b>by </b><i>, <a class="ref" href="altcat_1.html#D19">ALTCAT_1:def 19</a></i>
;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E5:76"/>
 <a href="altcat_1.html#K8">idm</a> <font color="Maroon">o</font> <a href="hidden.html#R1">=</a>  <a href="altcat_1.html#K8">idm</a> <font color="Maroon">o'</font>
 <b>by </b><i><a class="ref" href="altcat_1.html#D19">ALTCAT_1:def 19</a></i>;<br/>


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