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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">x3</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">x4</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>let </b><font color="Maroon">y3</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">y4</font> be    <a href="hidden.html#M1">set</a> ;<br/>















<b>assume </b><a NAME="E1:30"/>
<span class="p1"><a href="mcart_1.html#K4" target="_self">[</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font>,<font color="Maroon">x3</font>,<font color="Maroon">x4</font></span><a href="mcart_1.html#K4" target="_self">]</a></span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="mcart_1.html#K4" target="_self">[</a><span class="default"><font color="Maroon">y1</font>,<font color="Maroon">y2</font>,<font color="Maroon">y3</font>,<font color="Maroon">y4</font></span><a href="mcart_1.html#K4" target="_self">]</a></span>
 ;<br/>

<a NAME="E2:30"/><b>then </b>
<span class="p1"><a href="tarski.html#K4">[</a><span class="default"><span class="p2"><a href="mcart_1.html#K3" target="_self">[</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font>,<font color="Maroon">x3</font></span><a href="mcart_1.html#K3" target="_self">]</a></span>,<font color="Maroon">x4</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><span class="p2"><a href="mcart_1.html#K3" target="_self">[</a><span class="default"><font color="Maroon">y1</font>,<font color="Maroon">y2</font>,<font color="Maroon">y3</font></span><a href="mcart_1.html#K3" target="_self">]</a></span>,<font color="Maroon">y4</font></span><a href="tarski.html#K4">]</a></span>
 
;<br/>
<a NAME="E3:30"/><b>then </b>
( <span class="p1"><a href="mcart_1.html#K3" target="_self">[</a><span class="default"><font color="Maroon">x1</font>,<font color="Maroon">x2</font>,<font color="Maroon">x3</font></span><a href="mcart_1.html#K3" target="_self">]</a></span> <a href="hidden.html#R1">=</a> <span class="p1"><a href="mcart_1.html#K3" target="_self">[</a><span class="default"><font color="Maroon">y1</font>,<font color="Maroon">y2</font>,<font color="Maroon">y3</font></span><a href="mcart_1.html#K3" target="_self">]</a></span> &amp; <font color="Maroon">x4</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y4</font> )
 
<b>by </b><i><a class="ref" href="zfmisc_1.html#T33">ZFMISC_1:33</a></i>;<br/>
<b>hence </b><a NAME="E4:30"/>
( <font color="Maroon">x1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y1</font> &amp; <font color="Maroon">x2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y2</font> &amp; <font color="Maroon">x3</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y3</font> &amp; <font color="Maroon">x4</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y4</font> )
 <b>by </b><i/>;<br/>


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