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<b>let </b><font color="Maroon">A</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">o</font> be   <a href="binop_1.html#NM2">BinOp</a> of <font color="Maroon">A</font>;<br/><b>let </b><font color="Maroon">e1</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">A</font>;<br/><b>let </b><font color="Maroon">e2</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">A</font>;<br/>







<b>assume </b><a NAME="E1:21"/>
( <font color="Maroon">e1</font> <a href="binop_1.html#R1" target="_self">is_a_left_unity_wrt</a> <font color="Maroon">o</font> &amp; <font color="Maroon">e1</font> <a href="binop_1.html#R2" target="_self">is_a_right_unity_wrt</a> <font color="Maroon">o</font> &amp; <font color="Maroon">e2</font> <a href="binop_1.html#R1" target="_self">is_a_left_unity_wrt</a> <font color="Maroon">o</font> &amp; <font color="Maroon">e2</font> <a href="binop_1.html#R2" target="_self">is_a_right_unity_wrt</a> <font color="Maroon">o</font> )
 ; <i><font color="Red">:: according to </font></i><a class="ref" href="binop_1.html#D7" target="_self">BINOP_1:def 7</a><br/>

<b>hence </b><a NAME="E2:21"/>
<font color="Maroon">e1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">e2</font>
 <b>by </b><i/>;<br/>


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