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<b>let </b><font color="Maroon">c<sub>1</sub></font> be  <a href="xreal_0.html#V1">real</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>

<div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="28_1"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:28_1"/>
( <font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR4" target="_self">&gt;</a> 0 or <font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR3" target="_self">&lt;</a> 0 or <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> 0 )
 </span>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="28_1_1"><b>suppose </b></a><a NAME="E1:28_1_1"/><i><font color="Green">E16</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR4" target="_self">&gt;</a> 0
 ;<br/><div class="add"><a NAME="E2:28_1_1"/><b>then </b>
<font color="Maroon">c<sub>1</sub></font> <a href="prepower.html#K12">#R</a> 0 <a href="hidden.html#R1">=</a> 1
 <b>by </b><i><a class="ref" href="prepower.html#T85">PREPOWER:85</a></i>;<br/><b>hence </b><a NAME="E3:28_1_1"/>
<font color="Maroon">c<sub>1</sub></font> <a href="power.html#K3" target="_self">to_power</a> 0 <a href="hidden.html#R1">=</a> 1
 <b>by </b><i><a class="txt" href="power.html#E1:28_1_1"><i><font color="Green">E16</font></i></a>, <a class="ref" href="power.html#D2" target="_self">Def2</a></i>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="28_1_2"><b>suppose </b></a><a NAME="E1:28_1_2"/><i><font color="Green">E16</font></i>: 
<font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR3" target="_self">&lt;</a> 0
 ;<br/><div class="add"><b>reconsider </b><font color="Maroon">c<sub>2</sub></font> = 0 as   <a href="int_1.html#NM1">Integer</a> ;<br/><b>thus </b><font color="Maroon">c<sub>1</sub></font> <a href="power.html#K3" target="_self">to_power</a> 0 = 
<font color="Maroon">c<sub>1</sub></font> <a href="prepower.html#K6">#Z</a> <font color="Maroon">c<sub>2</sub></font>
<b>by </b><i><a class="txt" href="power.html#E1:28_1_2"><i><font color="Green">E16</font></i></a>, <a class="ref" href="power.html#D2" target="_self">Def2</a></i>
<br/>.= 
1
<b>by </b><i><a class="ref" href="prepower.html#T44">PREPOWER:44</a></i>
;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="28_1_3"><b>suppose </b></a><a NAME="E1:28_1_3"/>
<font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> 0
 ;<br/><div class="add"><b>hence </b><a NAME="E2:28_1_3"/>
<font color="Maroon">c<sub>1</sub></font> <a href="power.html#K3" target="_self">to_power</a> 0 <a href="hidden.html#R1">=</a> 1
 <b>by </b><i><a class="ref" href="power.html#D2" target="_self">Def2</a></i>;<br/></div><b>end;</b></div></div><b>end;</b></div>

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