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<a NAME="E1:5_2_1"/>
 <a href="xxreal_0.html#K2" target="_self">-infty</a>  <a href="hidden.html#R2">in</a> <span class="p1"><a href="tarski.html#K2">{</a><span class="default"><a href="numbers.html#K1">REAL</a> ,<span class="p2"><a href="tarski.html#K4">[</a><span class="default">0,<a href="numbers.html#K1">REAL</a> </span><a href="tarski.html#K4">]</a></span></span><a href="tarski.html#K2">}</a></span>
 
<b>by </b><i><a class="ref" href="tarski.html#D2">TARSKI:def 2</a></i>;<br/>
<a NAME="E2:5_2_1"/><b>then </b>
 <a href="xxreal_0.html#K2" target="_self">-infty</a>  <a href="hidden.html#R2">in</a>  <a href="numbers.html#K6">ExtREAL</a> 
 
<b>by </b><i><a class="ref" href="xboole_0.html#D2">XBOOLE_0:def 2</a></i>;<br/>
<b>hence </b><a NAME="E3:5_2_1"/>
 <a href="xxreal_0.html#K2" target="_self">-infty</a>  is <a href="xxreal_0.html#V1" target="_self">ext-real</a>
 <b>by </b><i><a class="ref" href="xxreal_0.html#D1" target="_self">Def1</a></i>;<br/>


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