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<b>let </b><font color="Maroon">x1</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">x2</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">y1</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">y2</font> be    <a href="hidden.html#M1">set</a> ;<br/>







<b>set </b><font color="Maroon">M</font> = <font color="Maroon">x1</font>,<font color="Maroon">x2</font> <a href="matrix_2.html#K3" target="_self">][</a> <font color="Maroon">y1</font>,<font color="Maroon">y2</font>;<br/>
<b>thus </b><a NAME="E1:6"/><i><font color="Green">E52</font></i>: 
 <a href="finseq_1.html#K3">len</a> <span class="p1">(<span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font> <a href="matrix_2.html#K3" target="_self">][</a> <font color="Maroon">y1</font>,<font color="Maroon">y2</font></span>)</span> <a href="hidden.html#R1">=</a> 2
 <b>by </b><i><a class="ref" href="finseq_1.html#T61">FINSEQ_1:61</a></i>;<br/>

<a NAME="E2:6"/>
 <a href="relat_1.html#K2">rng</a> <span class="p1">(<span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font> <a href="matrix_2.html#K3" target="_self">][</a> <font color="Maroon">y1</font>,<font color="Maroon">y2</font></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="tarski.html#K2">{</a><span class="default"><span class="p2"><a href="finseq_1.html#K10">&lt;*</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font></span><a href="finseq_1.html#K10">*&gt;</a></span>,<span class="p2"><a href="finseq_1.html#K10">&lt;*</a><span class="default"><font color="Maroon">y1</font>,<font color="Maroon">y2</font></span><a href="finseq_1.html#K10">*&gt;</a></span></span><a href="tarski.html#K2">}</a></span>
 
<b>by </b><i><a class="ref" href="finseq_2.html#T147">FINSEQ_2:147</a></i>;<br/>
<a NAME="E3:6"/><b>then </b>
( <span class="p1"><a href="finseq_1.html#K10">&lt;*</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font></span><a href="finseq_1.html#K10">*&gt;</a></span> <a href="hidden.html#R2">in</a>  <a href="relat_1.html#K2">rng</a> <span class="p1">(<span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font> <a href="matrix_2.html#K3" target="_self">][</a> <font color="Maroon">y1</font>,<font color="Maroon">y2</font></span>)</span> &amp;  <a href="finseq_1.html#K3">len</a> <span class="p1"><a href="finseq_1.html#K10">&lt;*</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font></span><a href="finseq_1.html#K10">*&gt;</a></span> <a href="hidden.html#R1">=</a> 2 &amp; 0 <a href="xxreal_0.html#NR3" target="_self">&lt;</a> 2 )
 
<b>by </b><i><a class="ref" href="finseq_1.html#T61">FINSEQ_1:61</a>, <a class="ref" href="tarski.html#D2">TARSKI:def 2</a></i>;<br/>
<b>hence </b><a NAME="E4:6"/>
 <a href="matrix_1.html#K1">width</a> <span class="p1">(<span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font> <a href="matrix_2.html#K3" target="_self">][</a> <font color="Maroon">y1</font>,<font color="Maroon">y2</font></span>)</span> <a href="hidden.html#R1">=</a> 2
 <b>by </b><i>, <a class="ref" href="matrix_1.html#D4">MATRIX_1:def 4</a></i>;<br/>

<b>hence </b><a NAME="E5:6"/>
 <a href="matrix_1.html#K2">Indices</a> <span class="p1">(<span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font> <a href="matrix_2.html#K3" target="_self">][</a> <font color="Maroon">y1</font>,<font color="Maroon">y2</font></span>)</span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="zfmisc_1.html#K2">[:</a><span class="default"><span class="p2">(<span class="default"><a href="finseq_1.html#K2">Seg</a> 2</span>)</span>,<span class="p2">(<span class="default"><a href="finseq_1.html#K2">Seg</a> 2</span>)</span></span><a href="zfmisc_1.html#K2">:]</a></span>
 <b>by </b><i>, <a class="ref" href="finseq_1.html#D3">FINSEQ_1:def 3</a></i>;<br/>


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