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<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="12_1"><b>now </b></a><div class="add"><b>assume </b><a NAME="E1:12_1"/>
 <a href="xxreal_0.html#K2" target="_self">-infty</a>  <a href="hidden.html#R1">=</a>  <a href="xxreal_0.html#K1" target="_self">+infty</a> 
 ;<br/><a NAME="E2:12_1"/><b>then </b>
<span class="p1"><a href="tarski.html#K2">{</a><span class="default">0,<a href="numbers.html#K1">REAL</a> </span><a href="tarski.html#K2">}</a></span> <a href="hidden.html#R2">in</a>  <a href="numbers.html#K1">REAL</a> 
 <b>by </b><i><a class="ref" href="tarski.html#D2">TARSKI:def 2</a></i>;<br/><b>hence </b><a NAME="E3:12_1"/>
 <a href="xxreal_0.html#K2" target="_self">-infty</a>  <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="xxreal_0.html#K1" target="_self">+infty</a> 
 <b>by </b><i><a class="ref" href="tarski.html#D2">TARSKI:def 2</a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E2:12"/>
 <a href="xxreal_0.html#K2" target="_self">-infty</a>  <a href="xxreal_0.html#NR3" target="_self">&lt;</a>  <a href="xxreal_0.html#K1" target="_self">+infty</a> 
 <b>by </b><i><a class="txt" href="xxreal_0.html#E8"><i><font color="Green">Lemma5</font></i></a>, <a class="txt" href="xxreal_0.html#E10"><i><font color="Green">Lemma7</font></i></a>, <a class="ref" href="xxreal_0.html#D5" target="_self">Def5</a></i>;<br/>


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