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<b>let </b><font color="Maroon">D</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">d1</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">D</font>;<br/><b>let </b><font color="Maroon">d2</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">D</font>;<br/><b>let </b><font color="Maroon">g</font> be   <a href="binop_1.html#NM2">BinOp</a> of <font color="Maroon">D</font>;<br/>







<b>assume </b><a NAME="E1:27"/><i><font color="Green">E35</font></i>: 
<font color="Maroon">g</font> is <a href="binop_1.html#V1">commutative</a>
 ;<br/>

<b>thus </b><font color="Maroon">g</font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1"><a href="finseq_4.html#K2">&lt;*</a><span class="default"><font color="Maroon">d1</font>,<font color="Maroon">d2</font></span><a href="finseq_4.html#K2">*&gt;</a></span> = 
<font color="Maroon">g</font> <a href="binop_1.html#K2">.</a> <font color="Maroon">d1</font>,<font color="Maroon">d2</font>
<b>by </b><i/>
<br/>.= 
<font color="Maroon">g</font> <a href="binop_1.html#K2">.</a> <font color="Maroon">d2</font>,<font color="Maroon">d1</font>
<b>by </b><i>, <a class="ref" href="binop_1.html#D2">BINOP_1:def 2</a></i>
<br/>.= 
<font color="Maroon">g</font> <a href="finsop_1.html#K2" target="_self">"**"</a> <span class="p1"><a href="finseq_4.html#K2">&lt;*</a><span class="default"><font color="Maroon">d2</font>,<font color="Maroon">d1</font></span><a href="finseq_4.html#K2">*&gt;</a></span>
<b>by </b><i/>
;<br/>


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