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<b>let </b><font color="Maroon">c<sub>1</sub></font> be    <a href="hidden.html#M1">set</a> ;<br/>

<a NAME="E1:15"/>
 <a href="xboole_0.html#K1">{}</a>  <a href="tarski.html#R1">c=</a>  <a href="partfun1.html#K6">id</a> <font color="Maroon">c<sub>1</sub></font>
 
<b>by </b><i><a class="ref" href="xboole_1.html#T2">XBOOLE_1:2</a></i>;<br/>
<b>hence </b><a NAME="E2:15"/>
<font color="Maroon">c<sub>1</sub></font> <a href="algspec1.html#K1" target="_self">-indexing</a> <a href="xboole_0.html#K1">{}</a>  <a href="hidden.html#R1">=</a>  <a href="partfun1.html#K6">id</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="ref" href="algspec1.html#T13" target="_self">Th13</a></i>;<br/>


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