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<b>let </b><font color="Maroon">c<sub>2</sub></font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>

<b>assume </b><a NAME="E1:21_2_1"/>
<font color="Maroon">c<sub>2</sub></font> is <a href="waybel23.html#V4" target="_self">sups-closed</a>
 ;<br/>

<b>then reconsider </b><font color="Maroon">c<sub>3</sub></font> =  <a href="yellow_0.html#K5">subrelstr</a> <font color="Maroon">c<sub>2</sub></font> as  <a href="yellow_0.html#V8">sups-inheriting</a>  <a href="yellow_0.html#M1">SubRelStr</a> of <font color="Maroon">c<sub>1</sub></font> <b>by </b><i><a class="ref" href="waybel23.html#D4" target="_self">Def4</a></i>;<br/>
<a NAME="E3:21_2_1"/>
<font color="Maroon">c<sub>3</sub></font> is <a href="yellow_0.html#V6">join-inheriting</a>
 
;<br/>
<b>hence </b><a NAME="E4:21_2_1"/>
<font color="Maroon">c<sub>2</sub></font> is <a href="waybel23.html#V2" target="_self">join-closed</a>
 <b>by </b><i><a class="ref" href="waybel23.html#D2" target="_self">Def2</a></i>;<br/>


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