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<b>let </b><font color="Maroon" title="c1">a</font>, <font color="Maroon" title="c2">b</font>, <font color="Maroon" title="c3">c</font>, <font color="Maroon" title="c4">d</font> be  <a href="xreal_0.html#V1" title="XREAL_0:attr.1">real</a>  <a href="ordinal1.html#NM1" title="ORDINAL1:NM.1">number</a> ;<br/>







<b>assume </b><a NAME="E1:5"/><i><font color="Green" title="E10">A1</font></i>: 
<font color="Maroon" title="c1">a</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <font color="Maroon" title="c2">b</font>
 ;<br/>

<b>assume </b><a NAME="E2:5"/>
<font color="Maroon" title="c3">c</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <font color="Maroon" title="c4">d</font>
 ;<br/>

<a NAME="E3:5"/><b>then </b><i><font color="Green" title="E11">A2</font></i>: 
<font color="Maroon" title="c2">b</font> <a href="xcmplx_0.html#K2" title="XCMPLX_0:func.2">+</a> <font color="Maroon" title="c3">c</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <font color="Maroon" title="c2">b</font> <a href="xcmplx_0.html#K2" title="XCMPLX_0:func.2">+</a> <font color="Maroon" title="c4">d</font>
 
<b>by </b><i><a class="txt" href="xreal_1.html#E8"><i><font color="Green" title="E8">Lm8</font></i></a></i>;<br/>
<a NAME="E4:5"/>
<font color="Maroon" title="c1">a</font> <a href="xcmplx_0.html#K2" title="XCMPLX_0:func.2">+</a> <font color="Maroon" title="c3">c</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <font color="Maroon" title="c2">b</font> <a href="xcmplx_0.html#K2" title="XCMPLX_0:func.2">+</a> <font color="Maroon" title="c3">c</font>
 
<b>by </b><i><a class="txt" href="xreal_1.html#E1:5"><i><font color="Green" title="E10">A1</font></i></a>, <a class="txt" href="xreal_1.html#E8"><i><font color="Green" title="E8">Lm8</font></i></a></i>;<br/>
<b>hence </b><a NAME="E5:5"/>
<font color="Maroon" title="c1">a</font> <a href="xcmplx_0.html#K2" title="XCMPLX_0:func.2">+</a> <font color="Maroon" title="c3">c</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <font color="Maroon" title="c2">b</font> <a href="xcmplx_0.html#K2" title="XCMPLX_0:func.2">+</a> <font color="Maroon" title="c4">d</font>
 <b>by </b><i><a class="txt" href="xreal_1.html#E3:5"><i><font color="Green" title="E11">A2</font></i></a>, <a class="txt" href="xreal_1.html#E4"><i><font color="Green" title="E4">Lm4</font></i></a></i>;<br/>


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