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<b>let </b><font color="Maroon">c<sub>3</sub></font> be    <a href="monoid_0.html#M2" target="_self">SubStr</a> of <font color="Maroon">c<sub>2</sub></font>;<br/>

<b>reconsider </b><font color="Maroon">c<sub>4</sub></font> = <font color="Maroon">c<sub>2</sub></font> as    <a href="monoid_0.html#M2" target="_self">SubStr</a> of <font color="Maroon">c<sub>1</sub></font> <b>by </b><i><a class="ref" href="monoid_0.html#T23" target="_self">Th23</a></i>;<br/>
<a NAME="E2:71_1_1"/>
<font color="Maroon">c<sub>3</sub></font> is    <a href="monoid_0.html#M5" target="_self">SubStr</a> of <font color="Maroon">c<sub>4</sub></font>
 
;<br/>
<b>hence </b><a NAME="E3:71_1_1"/>
<font color="Maroon">c<sub>3</sub></font> is    <a href="monoid_0.html#M2" target="_self">SubStr</a> of <font color="Maroon">c<sub>1</sub></font>
 ;<br/>


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