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<b>let </b><font color="Maroon" title="c1">X</font> be   <a href="bcialg_1.html#NM1" title="BCIALG_1:NM.1">BCI-algebra</a>;<br/><b>let </b><font color="Maroon" title="c2">x</font> be   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">X</font>;<br/>



<b>thus </b><a NAME="E1:43"/>
( <font color="Maroon" title="c2">x</font> is  <a href="bcialg_2.html#V1" title="BCIALG_2:attr.1">positive</a> <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">X</font> implies ( <font color="Maroon" title="c2">x</font> is <a href="bcialg_2.html#V5" title="BCIALG_2:attr.5">nilpotent</a> &amp;  <a href="bcialg_2.html#K2" title="BCIALG_2:func.2">ord</a> <font color="Maroon" title="c2">x</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> 1 ) )
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="43_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:43_1"/><i><font color="Green" title="E22">A1</font></i>: 
<font color="Maroon" title="c2">x</font> is  <a href="bcialg_2.html#V1" title="BCIALG_2:attr.1">positive</a> <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">X</font>
 ;<br/>

<a NAME="E2:43_1"/>
 <a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font> <a href="bcialg_1.html#R1" title="BCIALG_1:pred.1">&lt;=</a> <font color="Maroon" title="c2">x</font>
 
<b>by </b><i><a class="txt" href="bcialg_2.html#E1:43_1"><i><font color="Green" title="E22">A1</font></i></a>, <a class="ref" href="bcialg_2.html#D2" target="_self" title="BCIALG_2:def.2">Def2</a></i>;<br/>
<a NAME="E3:43_1"/><b>then </b><i><font color="Green" title="E23">A2</font></i>: 
<font color="Maroon" title="c2">x</font> <a href="bcialg_1.html#K2" title="BCIALG_1:func.2">`</a>  <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font>
 
<b>by </b><i><a class="ref" href="bcialg_1.html#D11" title="BCIALG_1:def.11">BCIALG_1:def 11</a></i>;<br/>
<b>thus </b><a NAME="E4:43_1"/><i><font color="Green" title="E24">A3</font></i>: 
<font color="Maroon" title="c2">x</font> is <a href="bcialg_2.html#V5" title="BCIALG_2:attr.5">nilpotent</a>
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="43_1_1"><b>proof </b></a><div class="add">

<b>set </b><font color="Maroon" title="c3">k</font> = 1;<br/>
<b>take </b>
1
; <i><font color="Red">:: according to </font></i><a class="ref" href="bcialg_2.html#D6" target="_self" title="BCIALG_2:def.6">BCIALG_2:def 6</a><br/>

<b>thus </b><a NAME="E1:43_1_1"/>
<span class="p1">(<span class="default"><a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font></span>)</span>,<font color="Maroon" title="c2">x</font> <a href="bcialg_2.html#K1" title="BCIALG_2:func.1">to_power</a> 1 <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font>
 <b>by </b><i><a class="txt" href="bcialg_2.html#E3:43_1"><i><font color="Green" title="E23">A2</font></i></a>, <a class="ref" href="bcialg_2.html#T2" target="_self" title="BCIALG_2:th.2">Th2</a></i>;<br/>


</div><b>end;</b></div>

<b>thus </b><a NAME="E5:43_1"/>
 <a href="bcialg_2.html#K2" title="BCIALG_2:func.2">ord</a> <font color="Maroon" title="c2">x</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> 1
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="43_1_2"><b>proof </b></a><div class="add">

<b>set </b><font color="Maroon" title="c3">k</font> = 1;<br/>
<b>reconsider </b><font color="Maroon" title="c4">k</font> = 1 as  non <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>  <a href="subset_1.html#M1" title="SUBSET_1:mode.1">Element</a> of  <a href="numbers.html#K5" title="NUMBERS:func.5">NAT</a>  ;<br/>
<a NAME="E2:43_1_2"/><i><font color="Green" title="E25">A4</font></i>: 
<span class="p1">(<span class="default"><a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font></span>)</span>,<font color="Maroon" title="c2">x</font> <a href="bcialg_2.html#K1" title="BCIALG_2:func.1">to_power</a> <font color="Maroon" title="c4">k</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font>
 
<b>by </b><i><a class="txt" href="bcialg_2.html#E3:43_1"><i><font color="Green" title="E23">A2</font></i></a>, <a class="ref" href="bcialg_2.html#T2" target="_self" title="BCIALG_2:th.2">Th2</a></i>;<br/>
<a NAME="E3:43_1_2"/>
for <font color="Olive" title="b1">m</font> being   <a href="subset_1.html#M1" title="SUBSET_1:mode.1">Element</a> of  <a href="numbers.html#K5" title="NUMBERS:func.5">NAT</a>   st <span class="p1">(<span class="default"><a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font></span>)</span>,<font color="Maroon" title="c2">x</font> <a href="bcialg_2.html#K1" title="BCIALG_2:func.1">to_power</a> <font color="Olive" title="b1">m</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font> &amp; <font color="Olive" title="b1">m</font> <a href="hidden.html#NR2" title="HIDDEN:NR.2">&lt;&gt;</a>  <a href="numbers.html#K6" title="NUMBERS:func.6">0</a>  holds <br/><font color="Maroon" title="c4">k</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <font color="Olive" title="b1">m</font>
 
<b>by </b><i><a class="ref" href="nat_1.html#T14" title="NAT_1:th.14">NAT_1:14</a></i>;<br/>
<b>hence </b><a NAME="E4:43_1_2"/>
 <a href="bcialg_2.html#K2" title="BCIALG_2:func.2">ord</a> <font color="Maroon" title="c2">x</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> 1
 <b>by </b><i><a class="txt" href="bcialg_2.html#E4:43_1"><i><font color="Green" title="E24">A3</font></i></a>, <a class="txt" href="bcialg_2.html#E2:43_1_2"><i><font color="Green" title="E25">A4</font></i></a>, <a class="ref" href="bcialg_2.html#D8" target="_self" title="BCIALG_2:def.8">Def8</a></i>;<br/>


</div><b>end;</b></div>


</div><b>end;</b></div>

<b>assume </b><a NAME="E2:43"/>
( <font color="Maroon" title="c2">x</font> is <a href="bcialg_2.html#V5" title="BCIALG_2:attr.5">nilpotent</a> &amp;  <a href="bcialg_2.html#K2" title="BCIALG_2:func.2">ord</a> <font color="Maroon" title="c2">x</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> 1 )
 ;<br/>

<a NAME="E3:43"/><b>then </b>
<span class="p1">(<span class="default"><a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font></span>)</span>,<font color="Maroon" title="c2">x</font> <a href="bcialg_2.html#K1" title="BCIALG_2:func.1">to_power</a> 1 <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font>
 
<b>by </b><i><a class="ref" href="bcialg_2.html#D8" target="_self" title="BCIALG_2:def.8">Def8</a></i>;<br/>
<a NAME="E4:43"/><b>then </b>
<font color="Maroon" title="c2">x</font> <a href="bcialg_1.html#K2" title="BCIALG_1:func.2">`</a>  <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font>
 
<b>by </b><i><a class="ref" href="bcialg_2.html#T2" target="_self" title="BCIALG_2:th.2">Th2</a></i>;<br/>
<a NAME="E5:43"/><b>then </b>
 <a href="struct_0.html#K4" title="STRUCT_0:func.4">0.</a> <font color="Maroon" title="c1">X</font> <a href="bcialg_1.html#R1" title="BCIALG_1:pred.1">&lt;=</a> <font color="Maroon" title="c2">x</font>
 
<b>by </b><i><a class="ref" href="bcialg_1.html#D11" title="BCIALG_1:def.11">BCIALG_1:def 11</a></i>;<br/>
<b>hence </b><a NAME="E6:43"/>
<font color="Maroon" title="c2">x</font> is  <a href="bcialg_2.html#V1" title="BCIALG_2:attr.1">positive</a> <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">X</font>
 <b>by </b><i><a class="ref" href="bcialg_2.html#D2" target="_self" title="BCIALG_2:def.2">Def2</a></i>;<br/>


</div>
