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

<b>let </b><font color="Maroon">X</font> be  non <a href="xboole_0.html#V1">empty</a> <a href="subset_1.html#NM2">Subset</a> of <a href="numbers.html#K6">ExtREAL</a> , <font color="Maroon">Y</font> be  non <a href="xboole_0.html#V1">empty</a> <a href="subset_1.html#NM2">Subset</a> of <a href="numbers.html#K6">ExtREAL</a> ;<br/>

<b>assume </b><a NAME="E1:36"/><i><font color="Green">E24</font></i>: 
( not <!--HUMANRECFAILED-->(  <a href="supinf_1.html#K2">-infty</a>  <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> &amp;  <a href="supinf_1.html#K1">+infty</a>  <a href="hidden.html#R2">in</a> <font color="Maroon">Y</font> ) &amp; not <!--HUMANRECFAILED-->(  <a href="supinf_1.html#K1">+infty</a>  <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> &amp;  <a href="supinf_1.html#K2">-infty</a>  <a href="hidden.html#R2">in</a> <font color="Maroon">Y</font> ) &amp; not <!--HUMANRECFAILED-->(  <a href="supinf_1.html#K7">inf</a> <font color="Maroon">X</font> <a href="hidden.html#R1">=</a>  <a href="supinf_1.html#K1">+infty</a>  &amp;  <a href="supinf_1.html#K7">inf</a> <font color="Maroon">Y</font> <a href="hidden.html#R1">=</a>  <a href="supinf_1.html#K2">-infty</a>  ) &amp; not <!--HUMANRECFAILED-->(  <a href="supinf_1.html#K7">inf</a> <font color="Maroon">X</font> <a href="hidden.html#R1">=</a>  <a href="supinf_1.html#K2">-infty</a>  &amp;  <a href="supinf_1.html#K7">inf</a> <font color="Maroon">Y</font> <a href="hidden.html#R1">=</a>  <a href="supinf_1.html#K1">+infty</a>  ) )
 ;<br/>

<a NAME="E2:36"/>
for <font color="Olive">z</font> being  <a href="supinf_1.html#NM3">R_eal</a>  st <font color="Olive">z</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> <a href="supinf_2.html#K5" target="_self">+</a> <font color="Maroon">Y</font> holds <br/><span class="p1">(<span class="default"><a href="supinf_1.html#K7">inf</a> <font color="Maroon">X</font></span>)</span> <a href="supinf_2.html#K2" target="_self">+</a> <span class="p1">(<span class="default"><a href="supinf_1.html#K7">inf</a> <font color="Maroon">Y</font></span>)</span> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Olive">z</font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="36_1"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon">z</font> be   <a href="supinf_1.html#NM3">R_eal</a>;<br/>

<b>assume </b><a NAME="E1:36_1"/>
<font color="Maroon">z</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> <a href="supinf_2.html#K5" target="_self">+</a> <font color="Maroon">Y</font>
 ;<br/>

<b>then consider </b><font color="Maroon">x</font> being   <a href="supinf_1.html#NM3">R_eal</a>, <font color="Maroon">y</font> being   <a href="supinf_1.html#NM3">R_eal</a><b> such that </b><br/><a NAME="E3:36_1"/><i><font color="Green">E28</font></i>: 
( <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> &amp; <font color="Maroon">y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">Y</font> &amp; <font color="Maroon">z</font> <a href="hidden.html#R1">=</a> <font color="Maroon">x</font> <a href="supinf_2.html#K2" target="_self">+</a> <font color="Maroon">y</font> )
 <b>by </b><i><a class="ref" href="supinf_2.html#T2" target="_self">Th2</a></i>;<br/>
<a NAME="E4:36_1"/>
(  <a href="supinf_1.html#K7">inf</a> <font color="Maroon">X</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">x</font> &amp;  <a href="supinf_1.html#K7">inf</a> <font color="Maroon">Y</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">y</font> )
 
<b>by </b><i><a class="ref" href="supinf_2.html#T3" target="_self">Th3</a>, <a class="ref" href="supinf_1.html#T79">SUPINF_1:79</a></i>;<br/>
<b>hence </b><a NAME="E5:36_1"/>
<span class="p1">(<span class="default"><a href="supinf_1.html#K7">inf</a> <font color="Maroon">X</font></span>)</span> <a href="supinf_2.html#K2" target="_self">+</a> <span class="p1">(<span class="default"><a href="supinf_1.html#K7">inf</a> <font color="Maroon">Y</font></span>)</span> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">z</font>
 <b>by </b><i>, <a class="ref" href="supinf_2.html#T3" target="_self">Th3</a>, </i>;<br/>


</div><b>end;</b></div>
<a NAME="E3:36"/><b>then </b>
<span class="p1">(<span class="default"><a href="supinf_1.html#K7">inf</a> <font color="Maroon">X</font></span>)</span> <a href="supinf_2.html#K2" target="_self">+</a> <span class="p1">(<span class="default"><a href="supinf_1.html#K7">inf</a> <font color="Maroon">Y</font></span>)</span> is    <a href="supinf_1.html#M2">minorant</a> of <font color="Maroon">X</font> <a href="supinf_2.html#K5" target="_self">+</a> <font color="Maroon">Y</font>
 
<b>by </b><i><a class="ref" href="supinf_1.html#D10">SUPINF_1:def 10</a></i>;<br/>
<b>hence </b><a NAME="E4:36"/>
<span class="p1">(<span class="default"><a href="supinf_1.html#K7">inf</a> <font color="Maroon">X</font></span>)</span> <a href="supinf_2.html#K2" target="_self">+</a> <span class="p1">(<span class="default"><a href="supinf_1.html#K7">inf</a> <font color="Maroon">Y</font></span>)</span> <a href="xxreal_0.html#R1">&lt;=</a>  <a href="supinf_1.html#K7">inf</a> <span class="p1">(<span class="default"><font color="Maroon">X</font> <a href="supinf_2.html#K5" target="_self">+</a> <font color="Maroon">Y</font></span>)</span>
 <b>by </b><i><a class="ref" href="supinf_1.html#D17">SUPINF_1:def 17</a></i>;<br/>


</div>
