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<b>let </b><font color="Maroon">C</font> be   <a href="conlat_1.html#NM1">FormalContext</a>;<br/><b>let </b><font color="Maroon">CS</font> be    <a href="conlat_1.html#L3">ConceptStr</a> of <font color="Maroon">C</font>;<br/>



<b>assume </b><a NAME="E1:21"/><i><font color="Green">E22</font></i>: 
( <span class="p1">(<span class="default"><a href="conlat_1.html#K1">ObjectDerivation</a> <font color="Maroon">C</font></span>)</span> <a href="funct_2.html#K3">.</a> the <a href="conlat_1.html#U4">Extent</a> of <font color="Maroon">CS</font> <a href="hidden.html#R1">=</a> the <a href="conlat_1.html#U5">Intent</a> of <font color="Maroon">CS</font> &amp; <span class="p1">(<span class="default"><a href="conlat_1.html#K2">AttributeDerivation</a> <font color="Maroon">C</font></span>)</span> <a href="funct_2.html#K3">.</a> the <a href="conlat_1.html#U5">Intent</a> of <font color="Maroon">CS</font> <a href="hidden.html#R1">=</a> the <a href="conlat_1.html#U4">Extent</a> of <font color="Maroon">CS</font> )
 ;<br/>

<div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="21_1"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:21_1"/>
( the <a href="conlat_1.html#U4">Extent</a> of <font color="Maroon">CS</font> is <a href="xboole_0.html#V1">empty</a> or  not the <a href="conlat_1.html#U4">Extent</a> of <font color="Maroon">CS</font> is <a href="xboole_0.html#V1">empty</a> )
 </span>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="21_1_1"><b>suppose </b></a><a NAME="E1:21_1_1"/>
the <a href="conlat_1.html#U4">Extent</a> of <font color="Maroon">CS</font> is <a href="xboole_0.html#V1">empty</a>
 ;<br/><div class="add"><a NAME="E2:21_1_1"/><b>then </b>
the <a href="conlat_1.html#U5">Intent</a> of <font color="Maroon">CS</font> <a href="hidden.html#R1">=</a> the <a href="conlat_1.html#U2">Attributes</a> of <font color="Maroon">C</font>
 <b>by </b><i>, <a class="ref" href="conlat_1.html#T18">CONLAT_1:18</a></i>;<br/><b>hence </b><a NAME="E3:21_1_1"/>
not <font color="Maroon">CS</font> is <a href="conlat_1.html#V7">empty</a>
 <b>by </b><i><a class="ref" href="conlat_1.html#D11">CONLAT_1:def 11</a></i>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="21_1_2"><b>suppose </b></a><a NAME="E1:21_1_2"/>
not the <a href="conlat_1.html#U4">Extent</a> of <font color="Maroon">CS</font> is <a href="xboole_0.html#V1">empty</a>
 ;<br/><div class="add"><b>hence </b><a NAME="E2:21_1_2"/>
not <font color="Maroon">CS</font> is <a href="conlat_1.html#V7">empty</a>
 <b>by </b><i><a class="ref" href="conlat_1.html#D11">CONLAT_1:def 11</a></i>;<br/></div><b>end;</b></div></div><b>end;</b></div>

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