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<b>let </b><font color="Maroon">K</font> be   <a href="vectsp_1.html#NM2">Field</a>;<br/><b>let </b><font color="Maroon">a</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">K</font>;<br/><b>let </b><font color="Maroon">b</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">K</font>;<br/><b>let </b><font color="Maroon">c</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">K</font>;<br/><b>let </b><font color="Maroon">d</font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">K</font>;<br/>









<b>set </b><font color="Maroon">M</font> = <font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font>;<br/>
<b>reconsider </b><font color="Maroon">id2</font> =  <a href="finseq_2.html#K1">idseq</a> 2 as   <a href="funct_2.html#NM2">Permutation</a> of  <a href="setwop_2.html#K2">Seg</a> 2 ;<br/>
<b>reconsider </b><font color="Maroon">Id2</font> =  <a href="finseq_2.html#K1">idseq</a> 2 as    <a href="matrix_2.html#M3">Element</a> of  <a href="matrix_2.html#K12">Permutations</a> 2 <b>by </b><i/>;<br/>
<b>reconsider </b><font color="Maroon">rid2</font> =  <a href="finseq_5.html#K3">Rev</a> <span class="p1">(<span class="default"><a href="finseq_2.html#K1">idseq</a> 2</span>)</span> as    <a href="matrix_2.html#M3">Element</a> of  <a href="matrix_2.html#K12">Permutations</a> 2 <b>by </b><i/>;<br/>
<b>set </b><font color="Maroon">F</font> = the <a href="rlvect_1.html#U1">add</a> of <font color="Maroon">K</font>;<br/>
<b>set </b><font color="Maroon">f</font> =  <a href="matrix_3.html#K11">Path_product</a> <span class="p1">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span>;<br/>
<a NAME="E4:22"/>
 <a href="matrix_2.html#K11">len</a> <span class="p1">(<span class="default"><a href="matrix_2.html#K12">Permutations</a> 2</span>)</span> <a href="hidden.html#R1">=</a> 2
 
<b>by </b><i><a class="ref" href="matrix_2.html#T20">MATRIX_2:20</a></i>;<br/>
<a NAME="E5:22"/><b>then </b><i><font color="Green">E31</font></i>: 
<font color="Maroon">Id2</font> is <a href="matrix_2.html#V3">even</a>
 
<b>by </b><i><a class="ref" href="matrix_2.html#T29">MATRIX_2:29</a></i>;<br/>
<i><font color="Green">E34</font></i>: <span class="p1">(<span class="default"><a href="matrix_3.html#K11">Path_product</a> <span class="p2">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">id2</font> = 
 <a href="matrix_2.html#K14">-</a> <span class="p1">(<span class="default">the <a href="group_1.html#U1">mult</a> of <font color="Maroon">K</font> <a href="finsop_1.html#K2">$$</a> <span class="p2">(<span class="default"><a href="matrix_3.html#K10">Path_matrix</a> <font color="Maroon">Id2</font>,<span class="p3">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span></span>)</span>,<font color="Maroon">Id2</font>
<b>by </b><i><a class="ref" href="matrix_3.html#D8">MATRIX_3:def 8</a></i>
<br/>.= 
the <a href="group_1.html#U1">mult</a> of <font color="Maroon">K</font> <a href="finsop_1.html#K2">$$</a> <span class="p1">(<span class="default"><a href="matrix_3.html#K10">Path_matrix</a> <font color="Maroon">Id2</font>,<span class="p2">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="matrix_2.html#D16">MATRIX_2:def 16</a>, </i>
<br/>.= 
the <a href="group_1.html#U1">mult</a> of <font color="Maroon">K</font> <a href="finsop_1.html#K2">$$</a> <span class="p1"><a href="finseq_4.html#K2">&lt;*</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">d</font></span><a href="finseq_4.html#K2">*&gt;</a></span>
<b>by </b><i/>
<br/>.= 
<font color="Maroon">a</font> <a href="group_1.html#K10">*</a> <font color="Maroon">d</font>
<b>by </b><i/>
;<br/>
<b>reconsider </b><font color="Maroon">f1</font> = <span class="p1">(<span class="default"><a href="matrix_3.html#K11">Path_product</a> <span class="p2">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">Id2</font>, <font color="Maroon">f2</font> = <span class="p1">(<span class="default"><a href="matrix_3.html#K11">Path_product</a> <span class="p2">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">rid2</font> as   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">K</font> ;<br/>
<a NAME="E8:22"/>
1 <a href="hidden.html#R2">in</a>  <a href="setwop_2.html#K2">Seg</a> 2
 
;<br/>
<a NAME="E9:22"/><b>then </b><i><font color="Green">E37</font></i>: 
<font color="Maroon">id2</font> <a href="funct_1.html#K1">.</a> 1 <a href="hidden.html#R1">=</a> 1
 
<b>by </b><i><a class="ref" href="funct_1.html#T35">FUNCT_1:35</a></i>;<br/>
<a NAME="E10:22"/><i><font color="Green">E38</font></i>: 
<font color="Maroon">rid2</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="finseq_4.html#K2">&lt;*</a><span class="default">2,1</span><a href="finseq_4.html#K2">*&gt;</a></span>
 
<b>by </b><i><a class="ref" href="finseq_5.html#T64">FINSEQ_5:64</a>, <a class="ref" href="finseq_2.html#T61">FINSEQ_2:61</a></i>;<br/>
<a NAME="E11:22"/><i><font color="Green">E39</font></i>: 
<font color="Maroon">id2</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">rid2</font>
 
<b>by </b><i>, </i>;<br/>
<a NAME="E12:22"/>
 <a href="matrix_2.html#K11">len</a> <span class="p1">(<span class="default"><a href="matrix_2.html#K12">Permutations</a> 2</span>)</span> <a href="hidden.html#R1">=</a> 2
 
<b>by </b><i><a class="ref" href="matrix_2.html#T20">MATRIX_2:20</a></i>;<br/>
<a NAME="E13:22"/><b>then </b><i><font color="Green">E40</font></i>: 
not <font color="Maroon">rid2</font> is <a href="matrix_2.html#V3">even</a>
 
<b>by </b><i>, </i>;<br/>
<i><font color="Green">E41</font></i>: <span class="p1">(<span class="default"><a href="matrix_3.html#K11">Path_product</a> <span class="p2">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">rid2</font> = 
 <a href="matrix_2.html#K14">-</a> <span class="p1">(<span class="default">the <a href="group_1.html#U1">mult</a> of <font color="Maroon">K</font> <a href="finsop_1.html#K2">$$</a> <span class="p2">(<span class="default"><a href="matrix_3.html#K10">Path_matrix</a> <font color="Maroon">rid2</font>,<span class="p3">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span></span>)</span>,<font color="Maroon">rid2</font>
<b>by </b><i><a class="ref" href="matrix_3.html#D8">MATRIX_3:def 8</a></i>
<br/>.= 
 <a href="rlvect_1.html#K5">-</a> <span class="p1">(<span class="default">the <a href="group_1.html#U1">mult</a> of <font color="Maroon">K</font> <a href="finsop_1.html#K2">$$</a> <span class="p2">(<span class="default"><a href="matrix_3.html#K10">Path_matrix</a> <font color="Maroon">rid2</font>,<span class="p3">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span></span>)</span>
<b>by </b><i>, <a class="ref" href="matrix_2.html#D16">MATRIX_2:def 16</a></i>
<br/>.= 
 <a href="rlvect_1.html#K5">-</a> <span class="p1">(<span class="default">the <a href="group_1.html#U1">mult</a> of <font color="Maroon">K</font> <a href="finsop_1.html#K2">$$</a> <span class="p2"><a href="finseq_4.html#K2">&lt;*</a><span class="default"><font color="Maroon">b</font>,<font color="Maroon">c</font></span><a href="finseq_4.html#K2">*&gt;</a></span></span>)</span>
<b>by </b><i/>
<br/>.= 
 <a href="rlvect_1.html#K5">-</a> <span class="p1">(<span class="default"><font color="Maroon">b</font> <a href="group_1.html#K10">*</a> <font color="Maroon">c</font></span>)</span>
<b>by </b><i/>
;<br/>
<a NAME="E15:22"/>
 <a href="matrix_2.html#K12">Permutations</a> 2 is <a href="finset_1.html#V1">finite</a>
 
<b>by </b><i><a class="ref" href="matrix_2.html#T30">MATRIX_2:30</a></i>;<br/>
<a NAME="E16:22"/><b>then </b><i><font color="Green">E42</font></i>: 
 <a href="matrix_2.html#K15">FinOmega</a> <span class="p1">(<span class="default"><a href="matrix_2.html#K12">Permutations</a> 2</span>)</span> <a href="hidden.html#R1">=</a>  <a href="matrix_2.html#K12">Permutations</a> 2
 
<b>by </b><i><a class="ref" href="matrix_2.html#D17">MATRIX_2:def 17</a></i>;<br/>
 <a href="matrix_3.html#K12">Det</a> <span class="p1">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span> = 
the <a href="rlvect_1.html#U1">add</a> of <font color="Maroon">K</font> <a href="setwiseo.html#K7">$$</a> <span class="p1"><a href="setwiseo.html#K3">{.</a><span class="default"><font color="Maroon">Id2</font>,<font color="Maroon">rid2</font></span><a href="setwiseo.html#K3">.}</a></span>,<span class="p1">(<span class="default"><a href="matrix_3.html#K11">Path_product</a> <span class="p2">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span>
<b>by </b><i>, , <a class="ref" href="matrix_3.html#D9">MATRIX_3:def 9</a></i>
<br/>.= 
the <a href="rlvect_1.html#U1">add</a> of <font color="Maroon">K</font> <a href="binop_1.html#K1">.</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="matrix_3.html#K11">Path_product</a> <span class="p3">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">id2</font></span>)</span>,<span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="matrix_3.html#K11">Path_product</a> <span class="p3">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">rid2</font></span>)</span>
<b>by </b><i>, <a class="ref" href="setwop_2.html#T3">SETWOP_2:3</a></i>
<br/>.= 
<span class="p1">(<span class="default"><font color="Maroon">a</font> <a href="group_1.html#K10">*</a> <font color="Maroon">d</font></span>)</span> <a href="rlvect_1.html#K6">-</a> <span class="p1">(<span class="default"><font color="Maroon">b</font> <a href="group_1.html#K10">*</a> <font color="Maroon">c</font></span>)</span>
<b>by </b><i>, </i>
;<br/>
<b>hence </b><a NAME="E18:22"/>
 <a href="matrix_3.html#K12">Det</a> <span class="p1">(<span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font> <a href="matrix_2.html#K6">][</a> <font color="Maroon">c</font>,<font color="Maroon">d</font></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">a</font> <a href="group_1.html#K10">*</a> <font color="Maroon">d</font></span>)</span> <a href="rlvect_1.html#K6">-</a> <span class="p1">(<span class="default"><font color="Maroon">b</font> <a href="group_1.html#K10">*</a> <font color="Maroon">c</font></span>)</span>
 ;<br/>


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