<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon">c<sub>1</sub></font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>3</sub></font> be   <a href="binop_1.html#NM2">BinOp</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>4</sub></font>, <font color="Maroon">c<sub>5</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/>









<b>defpred </b><font color="Maroon">S<sub>1</sub></font>[  <a href="nat_1.html#NM1">Nat</a>] means for <font color="Olive">b<sub>1</sub></font> being  <a href="binop_1.html#NM2">BinOp</a> of <font color="Maroon">c<sub>1</sub></font><br/>for <font color="Olive">b<sub>2</sub></font> being  <a href="nat_1.html#NM1">Nat</a><br/>for <font color="Olive">b<sub>3</sub></font> being   <a href="subset_1.html#M1">Element</a> of <font color="Maroon">c<sub>1</sub></font> st <font color="Olive">b<sub>1</sub></font> is <a href="binop_1.html#V2">associative</a> &amp; ( <font color="Olive">b<sub>1</sub></font> <a href="setwiseo.html#NR1" target="_self">has_a_unity</a>  or ( <font color="Olive">b<sub>2</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 &amp; <font color="Maroon">a<sub>1</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 ) ) holds <br/><font color="Olive">b<sub>1</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Olive">b<sub>2</sub></font> <a href="nat_1.html#K2">*</a> <font color="Maroon">a<sub>1</sub></font></span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Olive">b<sub>3</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Olive">b<sub>1</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><font color="Maroon">a<sub>1</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p2">(<span class="default"><font color="Olive">b<sub>1</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p3">(<span class="default"><font color="Olive">b<sub>2</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Olive">b<sub>3</sub></font></span>)</span></span>)</span></span>)</span>;<br/>
<a NAME="E1:33"/><i><font color="Green">E24</font></i>: 
<font color="Maroon">S<sub>1</sub></font>[0]
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="33_1"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon">c<sub>6</sub></font> be   <a href="binop_1.html#NM2">BinOp</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>7</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/><b>let </b><font color="Maroon">c<sub>8</sub></font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>





<b>assume </b><a NAME="E1:33_1"/>
( <font color="Maroon">c<sub>6</sub></font> is <a href="binop_1.html#V2">associative</a> &amp; ( <font color="Maroon">c<sub>6</sub></font> <a href="setwiseo.html#NR1" target="_self">has_a_unity</a>  or ( <font color="Maroon">c<sub>7</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 &amp; 0 <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 ) ) )
 ;<br/>

<b>thus </b><font color="Maroon">c<sub>6</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="nat_1.html#K2">*</a> 0</span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>8</sub></font></span>)</span> = 
<font color="Maroon">c<sub>6</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><a href="finseq_1.html#K6">&lt;*&gt;</a> <font color="Maroon">c<sub>1</sub></font></span>)</span>
<b>by </b><i><a class="ref" href="finseq_2.html#T72">FINSEQ_2:72</a></i>
<br/>.= 
<font color="Maroon">c<sub>6</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default">0 <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>8</sub></font></span>)</span></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="finseq_2.html#T72">FINSEQ_2:72</a></i>
;<br/>


</div><b>end;</b></div>
<a NAME="E2:33"/><i><font color="Green">E25</font></i>: 
for <font color="Olive">b<sub>1</sub></font> being  <a href="nat_1.html#NM1">Nat</a> st <font color="Maroon">S<sub>1</sub></font>[<font color="Olive">b<sub>1</sub></font>] holds <br/><font color="Maroon">S<sub>1</sub></font>[<font color="Olive">b<sub>1</sub></font> <a href="nat_1.html#K1">+</a> 1]
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="33_2"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon">c<sub>6</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/>

<b>assume </b><a NAME="E1:33_2"/><i><font color="Green">E26</font></i>: 
<font color="Maroon">S<sub>1</sub></font>[<font color="Maroon">c<sub>6</sub></font>]
 ;<br/>

<b>let </b><font color="Maroon">c<sub>7</sub></font> be   <a href="binop_1.html#NM2">BinOp</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>8</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/><b>let </b><font color="Maroon">c<sub>9</sub></font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>





<b>assume </b><b>that </b><br/><a NAME="E2:33_2"/><i><font color="Green">E27</font></i>: 
<font color="Maroon">c<sub>7</sub></font> is <a href="binop_1.html#V2">associative</a>
 <b>and </b><br/><a NAME="E3:33_2"/><i><font color="Green">E28</font></i>: 
( <font color="Maroon">c<sub>7</sub></font> <a href="setwiseo.html#NR1" target="_self">has_a_unity</a>  or ( <font color="Maroon">c<sub>8</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 &amp; <font color="Maroon">c<sub>6</sub></font> <a href="nat_1.html#K1">+</a> 1 <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 ) )
 ;<br/>

<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="33_2_1"><b>now </b></a><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="33_2_1_1"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:33_2_1_1"/>
( <font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#R1">=</a> 0 or <font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 )
 </span>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="33_2_1_1_1"><b>suppose </b></a><a NAME="E1:33_2_1_1_1"/>
<font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#R1">=</a> 0
 ;<br/><div class="add"><b>hence </b><a NAME="E2:33_2_1_1_1"/>
<font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="nat_1.html#K2">*</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="nat_1.html#K1">+</a> 1</span>)</span></span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="nat_1.html#K1">+</a> 1</span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span></span>)</span>
 <b>by </b><i><a class="ref" href="finsop_1.html#T17" target="_self">Th17</a></i>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="33_2_1_1_2"><b>suppose </b></a><a NAME="E1:33_2_1_1_2"/><i><font color="Green">E29</font></i>: 
<font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0
 ;<br/><div class="add"><a NAME="E2:33_2_1_1_2"/><b>then </b><i><font color="Green">E30</font></i>: 
( <font color="Maroon">c<sub>8</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 implies <font color="Maroon">c<sub>8</sub></font> <a href="nat_1.html#K2">*</a> <font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 )
 <b>by </b><i><a class="ref" href="xcmplx_1.html#T6">XCMPLX_1:6</a></i>;<br/><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="nat_1.html#K2">*</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="nat_1.html#K1">+</a> 1</span>)</span></span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span> = 
<font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><span class="p3">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="nat_1.html#K2">*</a> <font color="Maroon">c<sub>6</sub></font></span>)</span> <a href="nat_1.html#K1">+</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="nat_1.html#K2">*</a> 1</span>)</span></span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span>

<br/>.= 
<font color="Maroon">c<sub>7</sub></font> <a href="binop_1.html#K2">.</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p2">(<span class="default"><span class="p3">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="nat_1.html#K2">*</a> <font color="Maroon">c<sub>6</sub></font></span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span>,<span class="p1">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span>
<b>by </b><i><a class="txt" href="finsop_1.html#E2:33_2"><i><font color="Green">E27</font></i></a>, <a class="txt" href="finsop_1.html#E3:33_2"><i><font color="Green">E28</font></i></a>, <a class="txt" href="finsop_1.html#E2:33_2_1_1_2"><i><font color="Green">E30</font></i></a>, <a class="ref" href="finsop_1.html#T19" target="_self">Th19</a></i>
<br/>.= 
<font color="Maroon">c<sub>7</sub></font> <a href="binop_1.html#K2">.</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p4">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span></span>)</span></span>)</span>,<span class="p1">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span>
<b>by </b><i><a class="txt" href="finsop_1.html#E1:33_2"><i><font color="Green">E26</font></i></a>, <a class="txt" href="finsop_1.html#E2:33_2"><i><font color="Green">E27</font></i></a>, <a class="txt" href="finsop_1.html#E3:33_2"><i><font color="Green">E28</font></i></a>, <a class="txt" href="finsop_1.html#E1:33_2_1_1_2"><i><font color="Green">E29</font></i></a></i>
<br/>.= 
<font color="Maroon">c<sub>7</sub></font> <a href="binop_1.html#K2">.</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p4">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span></span>)</span></span>)</span>,<span class="p1">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p2">(<span class="default">1 <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p4">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="finsop_1.html#T17" target="_self">Th17</a></i>
;<br/><b>hence </b><a NAME="E4:33_2_1_1_2"/>
<font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="nat_1.html#K2">*</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="nat_1.html#K1">+</a> 1</span>)</span></span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="nat_1.html#K1">+</a> 1</span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span></span>)</span>
 <b>by </b><i><a class="txt" href="finsop_1.html#E2:33_2"><i><font color="Green">E27</font></i></a>, <a class="txt" href="finsop_1.html#E1:33_2_1_1_2"><i><font color="Green">E29</font></i></a>, <a class="ref" href="finsop_1.html#T19" target="_self">Th19</a></i>;<br/></div><b>end;</b></div></div><b>end;</b></div></div><b>end;</b></div>
<b>hence </b><a NAME="E5:33_2"/>
<font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="nat_1.html#K2">*</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="nat_1.html#K1">+</a> 1</span>)</span></span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>6</sub></font> <a href="nat_1.html#K1">+</a> 1</span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>7</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>8</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>9</sub></font></span>)</span></span>)</span></span>)</span>
 ;<br/>


</div><b>end;</b></div>
<a NAME="E3:33"/>
for <font color="Olive">b<sub>1</sub></font> being  <a href="nat_1.html#NM1">Nat</a> holds <font color="Maroon">S<sub>1</sub></font>[<font color="Olive">b<sub>1</sub></font>]
 
<b>from </b><i><a class="ref" href="nat_1.html#S1">NAT_1:sch 1</a>(<a class="txt" href="finsop_1.html#E1:33"><i><font color="Green">E24</font></i></a>, <a class="txt" href="finsop_1.html#E2:33"><i><font color="Green">E25</font></i></a>);<br/></i>
<b>hence </b><a NAME="E4:33"/>
( <font color="Maroon">c<sub>3</sub></font> is <a href="binop_1.html#V2">associative</a> &amp; ( <font color="Maroon">c<sub>3</sub></font> <a href="setwiseo.html#NR1" target="_self">has_a_unity</a>  or ( <font color="Maroon">c<sub>4</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 &amp; <font color="Maroon">c<sub>5</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 ) ) implies <font color="Maroon">c<sub>3</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>4</sub></font> <a href="nat_1.html#K2">*</a> <font color="Maroon">c<sub>5</sub></font></span>)</span> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>2</sub></font></span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>3</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>3</sub></font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p3">(<span class="default"><font color="Maroon">c<sub>4</sub></font> <a href="finsop_1.html#K1" target="_self">|-&gt;</a> <font color="Maroon">c<sub>2</sub></font></span>)</span></span>)</span></span>)</span> )
 ;<br/>


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