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<b>let </b><font color="Maroon">f</font> be   <a href="funct_2.html#NM1">Function</a> of  <a href="numbers.html#K1">REAL</a> , <a href="numbers.html#K1">REAL</a> ;<br/>

<a NAME="E1:26"/>
 <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> <a href="hidden.html#R1">=</a>  <a href="numbers.html#K1">REAL</a> 
 
<b>by </b><i><a class="ref" href="funct_2.html#D1">FUNCT_2:def 1</a></i>;<br/>
<b>then reconsider </b><font color="Maroon">B</font> =  <a href="relset_1.html#K5">rng</a> <font color="Maroon">f</font> as  non <a href="xboole_0.html#V1">empty</a> <a href="subset_1.html#NM2">Subset</a> of <a href="numbers.html#K1">REAL</a>  <b>by </b><i><a class="ref" href="relat_1.html#T65">RELAT_1:65</a></i>;<br/>
<a NAME="E3:26"/>
<font color="Maroon">f</font> is   <a href="struct_0.html#NM6">Function</a> of <a href="topalg_2.html#K3">R^1</a> ,<span class="p1">(<span class="default"><a href="topalg_2.html#K3">R^1</a>  <a href="pre_topc.html#K3">|</a> <span class="p2">(<span class="default"><a href="toprealb.html#K5" target="_self">R^1</a> <font color="Maroon">B</font></span>)</span></span>)</span>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E4:26"/>
<font color="Maroon">f</font> is   <a href="struct_0.html#NM6">Function</a> of <a href="topalg_2.html#K3">R^1</a> ,<a href="topalg_2.html#K3">R^1</a> 
 <b>by </b><i><a class="ref" href="topreala.html#T28">TOPREALA:28</a></i>;<br/>


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