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<b>let </b><font color="Maroon" title="c1">C</font> be   <a href="cat_1.html#NM4" title="CAT_1:NM.4">Category</a>;<br/><b>let </b><font color="Maroon" title="c2">c</font>, <font color="Maroon" title="c3">d</font> be   <a href="cat_1.html#NM1" title="CAT_1:NM.1">Object</a> of <font color="Maroon" title="c1">C</font>;<br/><b>let </b><font color="Maroon" title="c4">i1</font>, <font color="Maroon" title="c5">i2</font>, <font color="Maroon" title="c6">f</font> be   <a href="cat_1.html#NM2" title="CAT_1:NM.2">Morphism</a> of <font color="Maroon" title="c1">C</font>;<br/>











<b>assume </b><b>that </b><br/><a NAME="E1:103"/><i><font color="Green" title="E58">A1</font></i>: 
<font color="Maroon" title="c2">c</font> <a href="cat_3.html#R4" title="CAT_3:pred.4">is_a_coproduct_wrt</a> <font color="Maroon" title="c4">i1</font>,<font color="Maroon" title="c5">i2</font>
 <b>and </b><br/><a NAME="E2:103"/><i><font color="Green" title="E59">A2</font></i>: 
(  <a href="cat_1.html#K2" title="CAT_1:func.2">dom</a> <font color="Maroon" title="c6">f</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">c</font> &amp;  <a href="cat_1.html#K3" title="CAT_1:func.3">cod</a> <font color="Maroon" title="c6">f</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c3">d</font> &amp; <font color="Maroon" title="c6">f</font> is <a href="cat_1.html#V5" title="CAT_1:attr.5">invertible</a> )
 ;<br/>

<a NAME="E3:103"/>
(  <a href="cat_1.html#K3" title="CAT_1:func.3">cod</a> <font color="Maroon" title="c4">i1</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">c</font> &amp;  <a href="cat_1.html#K3" title="CAT_1:func.3">cod</a> <font color="Maroon" title="c5">i2</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">c</font> )
 
<b>by </b><i><a class="txt" href="cat_3.html#E1:103"><i><font color="Green" title="E58">A1</font></i></a>, <a class="ref" href="cat_3.html#D19" target="_self" title="CAT_3:def.19">Def19</a></i>;<br/>
<a NAME="E4:103"/><b>then </b>
( <font color="Maroon" title="c2">c</font> <a href="cat_3.html#R3" title="CAT_3:pred.3">is_a_coproduct_wrt</a> 0,1 <a href="funct_4.html#K5" title="FUNCT_4:func.5">--&gt;</a> <font color="Maroon" title="c4">i1</font>,<font color="Maroon" title="c5">i2</font> &amp; 0,1 <a href="funct_4.html#K5" title="FUNCT_4:func.5">--&gt;</a> <font color="Maroon" title="c4">i1</font>,<font color="Maroon" title="c5">i2</font> is    <a href="cat_3.html#M2" title="CAT_3:mode.2">Injections_family</a> of <font color="Maroon" title="c2">c</font>,<span class="p1"><a href="tarski.html#K2" title="TARSKI:func.2">{</a><span class="default">0,1</span><a href="tarski.html#K2" title="TARSKI:func.2">}</a></span> )
 
<b>by </b><i><a class="txt" href="cat_3.html#E1:103"><i><font color="Green" title="E58">A1</font></i></a>, <a class="ref" href="cat_3.html#T70" target="_self" title="CAT_3:th.70">Th70</a>, <a class="ref" href="cat_3.html#T85" target="_self" title="CAT_3:th.85">Th85</a></i>;<br/>
<a NAME="E5:103"/><b>then </b>
<font color="Maroon" title="c3">d</font> <a href="cat_3.html#R3" title="CAT_3:pred.3">is_a_coproduct_wrt</a> <font color="Maroon" title="c6">f</font> <a href="cat_3.html#K8" title="CAT_3:func.8">*</a> <span class="p1">(<span class="default">0,1 <a href="funct_4.html#K5" title="FUNCT_4:func.5">--&gt;</a> <font color="Maroon" title="c4">i1</font>,<font color="Maroon" title="c5">i2</font></span>)</span>
 
<b>by </b><i><a class="txt" href="cat_3.html#E2:103"><i><font color="Green" title="E59">A2</font></i></a>, <a class="ref" href="cat_3.html#T80" target="_self" title="CAT_3:th.80">Th80</a></i>;<br/>
<a NAME="E6:103"/><b>then </b>
<font color="Maroon" title="c3">d</font> <a href="cat_3.html#R3" title="CAT_3:pred.3">is_a_coproduct_wrt</a> 0,1 <a href="funct_4.html#K5" title="FUNCT_4:func.5">--&gt;</a> <span class="p1">(<span class="default"><font color="Maroon" title="c6">f</font> <a href="cat_1.html#K4" title="CAT_1:func.4">*</a> <font color="Maroon" title="c4">i1</font></span>)</span>,<span class="p1">(<span class="default"><font color="Maroon" title="c6">f</font> <a href="cat_1.html#K4" title="CAT_1:func.4">*</a> <font color="Maroon" title="c5">i2</font></span>)</span>
 
<b>by </b><i><a class="ref" href="cat_3.html#T19" target="_self" title="CAT_3:th.19">Th19</a></i>;<br/>
<b>hence </b><a NAME="E7:103"/>
<font color="Maroon" title="c3">d</font> <a href="cat_3.html#R4" title="CAT_3:pred.4">is_a_coproduct_wrt</a> <font color="Maroon" title="c6">f</font> <a href="cat_1.html#K4" title="CAT_1:func.4">*</a> <font color="Maroon" title="c4">i1</font>,<font color="Maroon" title="c6">f</font> <a href="cat_1.html#K4" title="CAT_1:func.4">*</a> <font color="Maroon" title="c5">i2</font>
 <b>by </b><i><a class="ref" href="cat_3.html#T85" target="_self" title="CAT_3:th.85">Th85</a></i>;<br/>


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