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

<b>let </b><font color="Maroon" title="c1">a1</font>, <font color="Maroon" title="c2">a2</font>, <font color="Maroon" title="c3">b1</font>, <font color="Maroon" title="c4">b2</font> be   <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a>;<br/>







<b>assume </b><a NAME="E1:43"/><i><font color="Green" title="E35">A1</font></i>: 
( <font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c2">a2</font> &amp; ( <font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c3">b1</font> or <font color="Maroon" title="c2">a2</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c4">b2</font> ) )
 ;<br/>

<a NAME="E2:43"/><i><font color="Green" title="E36">A2</font></i>: 
( <font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c3">b1</font> implies  ex <font color="Olive" title="b1">x</font> being  <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a> st <br/>( ( <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) or ( not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) ) )
 
<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"/>
<font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c3">b1</font>
 ;<br/>

<b>then consider </b><font color="Maroon" title="c5">x</font> being   <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a><b> such that </b><br/><a NAME="E3:43_1"/><i><font color="Green" title="E37">A3</font></i>: 
( <font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c5">x</font> &amp; <font color="Maroon" title="c5">x</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c3">b1</font> &amp; <font color="Maroon" title="c5">x</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c2">a2</font> &amp; <font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="supinf_1.html#K3" title="SUPINF_1:func.3">REAL</a>  )
 <b>by </b><i><a class="txt" href="measure5.html#E1:43"><i><font color="Green" title="E35">A1</font></i></a>, <a class="ref" href="measure5.html#T18" target="_self" title="MEASURE5:th.18">Th18</a></i>;<br/>
<a NAME="E4:43_1"/><i><font color="Green" title="E38">A4</font></i>: 
<font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span>
 
<b>by </b><i><a class="txt" href="measure5.html#E3:43_1"><i><font color="Green" title="E37">A3</font></i></a>, <a class="ref" href="measure5.html#D1" target="_self" title="MEASURE5:def.1">Def1</a></i>;<br/>
<a NAME="E5:43_1"/>
not <font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span>
 
<b>by </b><i><a class="txt" href="measure5.html#E3:43_1"><i><font color="Green" title="E37">A3</font></i></a>, <a class="ref" href="measure5.html#D1" target="_self" title="MEASURE5:def.1">Def1</a></i>;<br/>
<b>hence </b><a NAME="E6:43_1"/>
 ex <font color="Olive" title="b1">x</font> being  <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a> st <br/>( ( <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) or ( not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) )
 <b>by </b><i><a class="txt" href="measure5.html#E4:43_1"><i><font color="Green" title="E38">A4</font></i></a></i>;<br/>


</div><b>end;</b></div>
<div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="43_2"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:43_2"/>
( <font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c3">b1</font> or <font color="Maroon" title="c2">a2</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c4">b2</font> )
 </span><b>by </b><i><a class="txt" href="measure5.html#E1:43"><i><font color="Green" title="E35">A1</font></i></a></i>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="43_2_1"><b>suppose </b></a><a NAME="E1:43_2_1"/>
<font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c3">b1</font>
 ;<br/><div class="add"><b>hence </b><a NAME="E2:43_2_1"/>
 ex <font color="Olive" title="b1">x</font> being  <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a> st <br/>( ( <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) or ( not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) )
 <b>by </b><i><a class="txt" href="measure5.html#E2:43"><i><font color="Green" title="E36">A2</font></i></a></i>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="43_2_2"><b>suppose </b></a><a NAME="E1:43_2_2"/><i><font color="Green" title="E37">A5</font></i>: 
<font color="Maroon" title="c2">a2</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c4">b2</font>
 ;<br/><div class="add"><div><a class="txt" onclick="hs2(this)" href="javascript:()" title="43_2_2_1"><b>now </b></a><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="43_2_2_1_1"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:43_2_2_1_1"/>
( <font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c3">b1</font> or <font color="Maroon" title="c3">b1</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <font color="Maroon" title="c1">a1</font> )
 </span>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="43_2_2_1_1_1"><b>suppose </b></a><a NAME="E1:43_2_2_1_1_1"/>
<font color="Maroon" title="c1">a1</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c3">b1</font>
 ;<br/><div class="add"><b>hence </b><a NAME="E2:43_2_2_1_1_1"/>
 ex <font color="Olive" title="b1">x</font> being  <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a> st <br/>( ( <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) or ( not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) )
 <b>by </b><i><a class="txt" href="measure5.html#E2:43"><i><font color="Green" title="E36">A2</font></i></a></i>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="43_2_2_1_1_2"><b>suppose </b></a><a NAME="E1:43_2_2_1_1_2"/>
<font color="Maroon" title="c3">b1</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <font color="Maroon" title="c1">a1</font>
 ;<br/><div class="add"><a NAME="E2:43_2_2_1_1_2"/><b>then </b><i><font color="Green" title="E38">A6</font></i>: 
<span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <span class="p1"><a href="domain_1.html#K6" title="DOMAIN_1:func.6">{</a><span class="default"><font color="Maroon" title="c1">a1</font></span><a href="domain_1.html#K6" title="DOMAIN_1:func.6">}</a></span>
 <b>by </b><i><a class="ref" href="measure5.html#T15" target="_self" title="MEASURE5:th.15">Th15</a></i>;<br/><b>consider </b><font color="Maroon" title="c5">x</font> being   <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a><b> such that </b><br/><a NAME="E4:43_2_2_1_1_2"/><i><font color="Green" title="E39">A7</font></i>: 
( <font color="Maroon" title="c2">a2</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c5">x</font> &amp; <font color="Maroon" title="c5">x</font> <a href="xxreal_0.html#NR3" title="XXREAL_0:NR.3">&lt;</a> <font color="Maroon" title="c4">b2</font> &amp; <font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="supinf_1.html#K3" title="SUPINF_1:func.3">REAL</a>  )
 <b>by </b><i><a class="txt" href="measure5.html#E1:43_2_2"><i><font color="Green" title="E37">A5</font></i></a>, <a class="ref" href="measure5.html#T17" target="_self" title="MEASURE5:th.17">Th17</a></i>;<br/><a NAME="E5:43_2_2_1_1_2"/><i><font color="Green" title="E40">A8</font></i>: 
<font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span>
 <b>by </b><i><a class="txt" href="measure5.html#E4:43_2_2_1_1_2"><i><font color="Green" title="E39">A7</font></i></a>, <a class="ref" href="measure5.html#D1" target="_self" title="MEASURE5:def.1">Def1</a></i>;<br/><a NAME="E6:43_2_2_1_1_2"/>
not <font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span>
 <b>by </b><i><a class="txt" href="measure5.html#E1:43"><i><font color="Green" title="E35">A1</font></i></a>, <a class="txt" href="measure5.html#E2:43_2_2_1_1_2"><i><font color="Green" title="E38">A6</font></i></a>, <a class="txt" href="measure5.html#E4:43_2_2_1_1_2"><i><font color="Green" title="E39">A7</font></i></a>, <a class="ref" href="tarski.html#D1" title="TARSKI:def.1">TARSKI:def 1</a></i>;<br/><b>hence </b><a NAME="E7:43_2_2_1_1_2"/>
 ex <font color="Olive" title="b1">x</font> being  <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a> st <br/>( ( <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) or ( not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) )
 <b>by </b><i><a class="txt" href="measure5.html#E5:43_2_2_1_1_2"><i><font color="Green" title="E40">A8</font></i></a></i>;<br/></div><b>end;</b></div></div><b>end;</b></div></div><b>end;</b></div><b>hence </b><a NAME="E3:43_2_2"/>
 ex <font color="Olive" title="b1">x</font> being  <a href="supinf_1.html#NM3" title="SUPINF_1:NM.3">R_eal</a> st <br/>( ( <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) or ( not <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c1">a1</font>,<font color="Maroon" title="c3">b1</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> &amp; <font color="Olive" title="b1">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="measure5.html#K1" title="MEASURE5:func.1">[.</a><span class="default"><font color="Maroon" title="c2">a2</font>,<font color="Maroon" title="c4">b2</font></span><a href="measure5.html#K1" title="MEASURE5:func.1">.]</a></span> ) )
 ;<br/></div><b>end;</b></div></div><b>end;</b></div>

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