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<b>let </b><font color="Maroon">a</font> be   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">b</font> be   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">c</font> be   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">d</font> be   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">e</font> be   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">f</font> be   <a href="real_1.html#NM1">Real</a>;<br/>

<b>assume </b><a NAME="E1:3"/>
( <font color="Maroon">a</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">b</font> <a href="real_1.html#K3">+</a> <font color="Maroon">c</font> &amp; <font color="Maroon">d</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">e</font> <a href="real_1.html#K3">+</a> <font color="Maroon">f</font> )
 ;<br/>

<a NAME="E2:3"/><b>then </b>
(  <a href="square_1.html#K2">max</a> <font color="Maroon">a</font>,<font color="Maroon">d</font> <a href="xxreal_0.html#R1">&lt;=</a>  <a href="square_1.html#K2">max</a> <span class="p1">(<span class="default"><font color="Maroon">b</font> <a href="real_1.html#K3">+</a> <font color="Maroon">c</font></span>)</span>,<span class="p1">(<span class="default"><font color="Maroon">e</font> <a href="real_1.html#K3">+</a> <font color="Maroon">f</font></span>)</span> &amp;  <a href="square_1.html#K2">max</a> <span class="p1">(<span class="default"><font color="Maroon">b</font> <a href="real_1.html#K3">+</a> <font color="Maroon">c</font></span>)</span>,<span class="p1">(<span class="default"><font color="Maroon">e</font> <a href="real_1.html#K3">+</a> <font color="Maroon">f</font></span>)</span> <a href="xxreal_0.html#R1">&lt;=</a> <span class="p1">(<span class="default"><a href="square_1.html#K2">max</a> <font color="Maroon">b</font>,<font color="Maroon">e</font></span>)</span> <a href="real_1.html#K3">+</a> <span class="p1">(<span class="default"><a href="square_1.html#K2">max</a> <font color="Maroon">c</font>,<font color="Maroon">f</font></span>)</span> )
 
<b>by </b><i>, <a class="ref" href="xxreal_0.html#T26">XXREAL_0:26</a></i>;<br/>
<b>hence </b><a NAME="E3:3"/>
 <a href="square_1.html#K2">max</a> <font color="Maroon">a</font>,<font color="Maroon">d</font> <a href="xxreal_0.html#R1">&lt;=</a> <span class="p1">(<span class="default"><a href="square_1.html#K2">max</a> <font color="Maroon">b</font>,<font color="Maroon">e</font></span>)</span> <a href="real_1.html#K3">+</a> <span class="p1">(<span class="default"><a href="square_1.html#K2">max</a> <font color="Maroon">c</font>,<font color="Maroon">f</font></span>)</span>
 <b>by </b><i><a class="ref" href="xxreal_0.html#T2">XXREAL_0:2</a></i>;<br/>


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