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<b>let </b><font color="Maroon">C</font> be   <a href="cat_4.html#NM2">Cocartesian_category</a>;<br/><b>let </b><font color="Maroon">a</font> be   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">c</font> be   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">b</font> be   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">d</font> be   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">e</font> be   <a href="cat_1.html#NM1">Object</a> of <font color="Maroon">C</font>;<br/><b>let </b><font color="Maroon">f</font> be    <a href="cat_1.html#M1">Morphism</a> of <font color="Maroon">a</font>,<font color="Maroon">c</font>;<br/><b>let </b><font color="Maroon">h</font> be    <a href="cat_1.html#M1">Morphism</a> of <font color="Maroon">b</font>,<font color="Maroon">d</font>;<br/><b>let </b><font color="Maroon">g</font> be    <a href="cat_1.html#M1">Morphism</a> of <font color="Maroon">c</font>,<font color="Maroon">e</font>;<br/><b>let </b><font color="Maroon">k</font> be    <a href="cat_1.html#M1">Morphism</a> of <font color="Maroon">d</font>,<font color="Maroon">e</font>;<br/>



















<b>assume </b><b>that </b><br/><a NAME="E1:104"/><i><font color="Green">E34</font></i>: 
 <a href="cat_1.html#K6">Hom</a> <font color="Maroon">a</font>,<font color="Maroon">c</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 <b>and </b><br/><a NAME="E2:104"/><i><font color="Green">E35</font></i>: 
 <a href="cat_1.html#K6">Hom</a> <font color="Maroon">b</font>,<font color="Maroon">d</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 <b>and </b><br/><a NAME="E3:104"/><i><font color="Green">E36</font></i>: 
 <a href="cat_1.html#K6">Hom</a> <font color="Maroon">c</font>,<font color="Maroon">e</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 <b>and </b><br/><a NAME="E4:104"/><i><font color="Green">E37</font></i>: 
 <a href="cat_1.html#K6">Hom</a> <font color="Maroon">d</font>,<font color="Maroon">e</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 ;<br/>

<a NAME="E5:104"/><i><font color="Green">E38</font></i>: 
 <a href="cat_1.html#K6">Hom</a> <span class="p1">(<span class="default"><font color="Maroon">c</font> <a href="cat_4.html#K20" target="_self">+</a> <font color="Maroon">d</font></span>)</span>,<font color="Maroon">e</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a> 
 
<b>by </b><i>, , </i>;<br/>
<a NAME="E6:104"/>
(  <a href="cat_1.html#K6">Hom</a> <font color="Maroon">c</font>,<span class="p1">(<span class="default"><font color="Maroon">c</font> <a href="cat_4.html#K20" target="_self">+</a> <font color="Maroon">d</font></span>)</span> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a>  &amp;  <a href="cat_1.html#K6">Hom</a> <font color="Maroon">d</font>,<span class="p1">(<span class="default"><font color="Maroon">c</font> <a href="cat_4.html#K20" target="_self">+</a> <font color="Maroon">d</font></span>)</span> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a>  &amp; <span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><font color="Maroon">g</font>,<font color="Maroon">k</font></span><a href="cat_4.html#K27" target="_self">$]</a></span> <a href="cat_1.html#K9">*</a> <span class="p1">(<span class="default"><a href="cat_4.html#K25" target="_self">in1</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">g</font> &amp; <span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><font color="Maroon">g</font>,<font color="Maroon">k</font></span><a href="cat_4.html#K27" target="_self">$]</a></span> <a href="cat_1.html#K9">*</a> <span class="p1">(<span class="default"><a href="cat_4.html#K26" target="_self">in2</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">k</font> )
 
<b>by </b><i>, , , </i>;<br/>
<a NAME="E7:104"/><b>then </b>
(  <a href="cat_1.html#K6">Hom</a> <font color="Maroon">a</font>,<span class="p1">(<span class="default"><font color="Maroon">c</font> <a href="cat_4.html#K20" target="_self">+</a> <font color="Maroon">d</font></span>)</span> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a>  &amp;  <a href="cat_1.html#K6">Hom</a> <font color="Maroon">b</font>,<span class="p1">(<span class="default"><font color="Maroon">c</font> <a href="cat_4.html#K20" target="_self">+</a> <font color="Maroon">d</font></span>)</span> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xboole_0.html#K1">{}</a>  &amp; <font color="Maroon">g</font> <a href="cat_1.html#K9">*</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><font color="Maroon">g</font>,<font color="Maroon">k</font></span><a href="cat_4.html#K27" target="_self">$]</a></span> <a href="cat_1.html#K9">*</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="cat_4.html#K25" target="_self">in1</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span> <a href="cat_1.html#K9">*</a> <font color="Maroon">f</font></span>)</span> &amp; <font color="Maroon">k</font> <a href="cat_1.html#K9">*</a> <font color="Maroon">h</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><font color="Maroon">g</font>,<font color="Maroon">k</font></span><a href="cat_4.html#K27" target="_self">$]</a></span> <a href="cat_1.html#K9">*</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="cat_4.html#K26" target="_self">in2</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span> <a href="cat_1.html#K9">*</a> <font color="Maroon">h</font></span>)</span> )
 
<b>by </b><i>, , , <a class="ref" href="cat_1.html#T52">CAT_1:52</a>, <a class="ref" href="cat_1.html#T54">CAT_1:54</a></i>;<br/>
<a NAME="E8:104"/><b>then </b>
<span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon">g</font> <a href="cat_1.html#K9">*</a> <font color="Maroon">f</font></span>)</span>,<span class="p2">(<span class="default"><font color="Maroon">k</font> <a href="cat_1.html#K9">*</a> <font color="Maroon">h</font></span>)</span></span><a href="cat_4.html#K27" target="_self">$]</a></span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><font color="Maroon">g</font>,<font color="Maroon">k</font></span><a href="cat_4.html#K27" target="_self">$]</a></span> <a href="cat_1.html#K9">*</a> <span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><span class="p2">(<span class="default"><span class="p3">(<span class="default"><a href="cat_4.html#K25" target="_self">in1</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span> <a href="cat_1.html#K9">*</a> <font color="Maroon">f</font></span>)</span>,<span class="p2">(<span class="default"><span class="p3">(<span class="default"><a href="cat_4.html#K26" target="_self">in2</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span> <a href="cat_1.html#K9">*</a> <font color="Maroon">h</font></span>)</span></span><a href="cat_4.html#K27" target="_self">$]</a></span>
 
<b>by </b><i>, </i>;<br/>
<b>hence </b><a NAME="E9:104"/>
<span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><font color="Maroon">g</font>,<font color="Maroon">k</font></span><a href="cat_4.html#K27" target="_self">$]</a></span> <a href="cat_1.html#K9">*</a> <span class="p1">(<span class="default"><font color="Maroon">f</font> <a href="cat_4.html#K29" target="_self">+</a> <font color="Maroon">h</font></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="cat_4.html#K27" target="_self">[$</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon">g</font> <a href="cat_1.html#K9">*</a> <font color="Maroon">f</font></span>)</span>,<span class="p2">(<span class="default"><font color="Maroon">k</font> <a href="cat_1.html#K9">*</a> <font color="Maroon">h</font></span>)</span></span><a href="cat_4.html#K27" target="_self">$]</a></span>
 ;<br/>


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