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<b>let </b><font color="Maroon">c<sub>4</sub></font> be   <a href="vectsp_1.html#NM2">Field</a>;<br/><b>let </b><font color="Maroon">c<sub>5</sub></font> be   <a href="symsp_1.html#NM1">SymSp</a> of <font color="Maroon">c<sub>4</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>6</sub></font>, <font color="Maroon">c<sub>7</sub></font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>5</sub></font>;<br/>







<b>assume </b><a NAME="E1:21"/><i><font color="Green">E17</font></i>: 
( <font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="rlvect_1.html#K1">0.</a> <font color="Maroon">c<sub>5</sub></font> &amp; <font color="Maroon">c<sub>7</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="rlvect_1.html#K1">0.</a> <font color="Maroon">c<sub>5</sub></font> )
 ;<br/>

<b>then consider </b><font color="Maroon">c<sub>8</sub></font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>5</sub></font><b> such that </b><br/><a NAME="E3:21"/><i><font color="Green">E18</font></i>: 
not <font color="Maroon">c<sub>8</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>6</sub></font>
 <b>by </b><i><a class="ref" href="symsp_1.html#D2" target="_self">Def2</a></i>;<br/>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="21_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:21_1"/><i><font color="Green">E19</font></i>: 
<font color="Maroon">c<sub>8</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>7</sub></font>
 ;<br/><b>consider </b><font color="Maroon">c<sub>9</sub></font> being   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>5</sub></font><b> such that </b><br/><a NAME="E3:21_1"/><i><font color="Green">E20</font></i>: 
not <font color="Maroon">c<sub>9</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>7</sub></font>
 <b>by </b><i><a class="txt" href="symsp_1.html#E1:21"><i><font color="Green">E17</font></i></a>, <a class="ref" href="symsp_1.html#D2" target="_self">Def2</a></i>;<br/><div><a class="txt" onclick="hs2(this)" href="javascript:()" title="21_1_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:21_1_1"/>
<font color="Maroon">c<sub>9</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>6</sub></font>
 ;<br/><a NAME="E2:21_1_1"/><b>then </b>
( not <font color="Maroon">c<sub>8</sub></font> <a href="rlvect_1.html#K4">+</a> <font color="Maroon">c<sub>9</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>6</sub></font> &amp; not <font color="Maroon">c<sub>8</sub></font> <a href="rlvect_1.html#K4">+</a> <font color="Maroon">c<sub>9</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>7</sub></font> )
 <b>by </b><i><a class="txt" href="symsp_1.html#E3:21"><i><font color="Green">E18</font></i></a>, <a class="txt" href="symsp_1.html#E1:21_1"><i><font color="Green">E19</font></i></a>, <a class="txt" href="symsp_1.html#E3:21_1"><i><font color="Green">E20</font></i></a>, <a class="ref" href="symsp_1.html#T20" target="_self">Th20</a></i>;<br/><b>hence </b><a NAME="E3:21_1_1"/>
ex <font color="Olive">b<sub>1</sub></font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>5</sub></font> st <br/>( not <font color="Olive">b<sub>1</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>6</sub></font> &amp; not <font color="Olive">b<sub>1</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>7</sub></font> )
 ;<br/></div><b>end;</b></div><b>hence </b><a NAME="E5:21_1"/>
ex <font color="Olive">b<sub>1</sub></font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>5</sub></font> st <br/>( not <font color="Olive">b<sub>1</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>6</sub></font> &amp; not <font color="Olive">b<sub>1</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>7</sub></font> )
 <b>by </b><i><a class="txt" href="symsp_1.html#E3:21_1"><i><font color="Green">E20</font></i></a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E5:21"/>
ex <font color="Olive">b<sub>1</sub></font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>5</sub></font> st <br/>( not <font color="Olive">b<sub>1</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>6</sub></font> &amp; not <font color="Olive">b<sub>1</sub></font> <a href="symsp_1.html#R1" target="_self">_|_</a> <font color="Maroon">c<sub>7</sub></font> )
 <b>by </b><i><a class="txt" href="symsp_1.html#E3:21"><i><font color="Green">E18</font></i></a></i>;<br/>


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