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<b>thus </b><a NAME="E1:17_1_1"/>
( <font color="Maroon">w</font> <a href="hidden.html#R1">=</a> 0 &amp; <font color="Maroon">z</font> <a href="hidden.html#R1">=</a> 0 implies <span class="p1"><a href="arytm_0.html#K5">[*</a><span class="default"><font color="Maroon">x</font>,<font color="Maroon">y</font></span><a href="arytm_0.html#K5">*]</a></span> is    <a href="subset_1.html#M1">Element</a> of  <a href="quaterni.html#K1" target="_self">QUATERNION</a>  )
 <b>by </b><i><a class="ref" href="xboole_0.html#D2">XBOOLE_0:def 2</a></i>;<br/>

<b>set </b><font color="Maroon">e</font> = 0,1,2,3 <a href="quaterni.html#K3" target="_self">--&gt;</a> <font color="Maroon">x</font>,<font color="Maroon">y</font>,<font color="Maroon">w</font>,<font color="Maroon">z</font>;<br/>
<b>assume </b><a NAME="E2:17_1_1"/><i><font color="Green">E37</font></i>: 
( <font color="Maroon">w</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 or <font color="Maroon">z</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 )
 ;<br/>

<a NAME="E3:17_1_1"/><i><font color="Green">E40</font></i>: 
0,1,2,3 <a href="quaterni.html#K3" target="_self">--&gt;</a> <font color="Maroon">x</font>,<font color="Maroon">y</font>,<font color="Maroon">w</font>,<font color="Maroon">z</font> <a href="hidden.html#R2">in</a>  <a href="funct_2.html#K1">Funcs</a> 4,<a href="numbers.html#K1">REAL</a> 
 
<b>by </b><i><a class="ref" href="funct_2.html#T11">FUNCT_2:11</a>, <a class="ref" href="card_1.html#T90">CARD_1:90</a></i>;<br/>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="17_1_1_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:17_1_1_1"/>
0,1,2,3 <a href="quaterni.html#K3" target="_self">--&gt;</a> <font color="Maroon">x</font>,<font color="Maroon">y</font>,<font color="Maroon">w</font>,<font color="Maroon">z</font> <a href="hidden.html#R2">in</a> <span class="p1">{<span class="default"> <font color="Olive">r</font> where <font color="Olive">r</font> is    <a href="subset_1.html#M1">Element</a> of  <a href="funct_2.html#K1">Funcs</a> 4,<a href="numbers.html#K1">REAL</a>  : ( <font color="Olive">r</font> <a href="funct_1.html#K1">.</a> 2 <a href="hidden.html#R1">=</a> 0 &amp; <font color="Olive">r</font> <a href="funct_1.html#K1">.</a> 3 <a href="hidden.html#R1">=</a> 0 ) </span>}</span> 
 ;<br/><a NAME="E2:17_1_1_1"/><b>then </b>
 ex <font color="Olive">r</font> being   <a href="subset_1.html#M1">Element</a> of  <a href="funct_2.html#K1">Funcs</a> 4,<a href="numbers.html#K1">REAL</a>  st <br/>( 0,1,2,3 <a href="quaterni.html#K3" target="_self">--&gt;</a> <font color="Maroon">x</font>,<font color="Maroon">y</font>,<font color="Maroon">w</font>,<font color="Maroon">z</font> <a href="hidden.html#R1">=</a> <font color="Olive">r</font> &amp; <font color="Olive">r</font> <a href="funct_1.html#K1">.</a> 2 <a href="hidden.html#R1">=</a> 0 &amp; <font color="Olive">r</font> <a href="funct_1.html#K1">.</a> 3 <a href="hidden.html#R1">=</a> 0 )
 ;<br/><b>hence </b><a NAME="E3:17_1_1_1"/>
contradiction
 <b>by </b><i>, , </i>;<br/></div><b>end;</b></div>
<a NAME="E5:17_1_1"/><b>then </b>
0,1,2,3 <a href="quaterni.html#K3" target="_self">--&gt;</a> <font color="Maroon">x</font>,<font color="Maroon">y</font>,<font color="Maroon">w</font>,<font color="Maroon">z</font> <a href="hidden.html#R2">in</a> <span class="p1">(<span class="default"><a href="funct_2.html#K1">Funcs</a> 4,<a href="numbers.html#K1">REAL</a> </span>)</span> <a href="subset_1.html#K6">\</a> <span class="p1">{<span class="default"> <font color="Olive">r</font> where <font color="Olive">r</font> is    <a href="subset_1.html#M1">Element</a> of  <a href="funct_2.html#K1">Funcs</a> 4,<a href="numbers.html#K1">REAL</a>  : ( <font color="Olive">r</font> <a href="funct_1.html#K1">.</a> 2 <a href="hidden.html#R1">=</a> 0 &amp; <font color="Olive">r</font> <a href="funct_1.html#K1">.</a> 3 <a href="hidden.html#R1">=</a> 0 ) </span>}</span> 
 
<b>by </b><i>, <a class="ref" href="xboole_0.html#D4">XBOOLE_0:def 4</a></i>;<br/>
<b>hence </b><a NAME="E6:17_1_1"/>
0,1,2,3 <a href="quaterni.html#K3" target="_self">--&gt;</a> <font color="Maroon">x</font>,<font color="Maroon">y</font>,<font color="Maroon">w</font>,<font color="Maroon">z</font> is    <a href="subset_1.html#M1">Element</a> of  <a href="quaterni.html#K1" target="_self">QUATERNION</a> 
 <b>by </b><i><a class="ref" href="xboole_0.html#D2">XBOOLE_0:def 2</a></i>;<br/>


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