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<b>let </b><font color="Maroon">c<sub>1</sub></font> be  non <a href="struct_0.html#V3">empty</a>  <a href="rlvect_1.html#L1">LoopStr</a> ;<br/>

<b>assume </b><a NAME="E1:4_2_1"/><i><font color="Green">E2</font></i>: 
( <font color="Maroon">c<sub>1</sub></font> is <a href="rlvect_1.html#V3">Abelian</a> &amp; <font color="Maroon">c<sub>1</sub></font> is <a href="algstr_1.html#V2">add-left-cancelable</a> )
 ;<br/>

<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="4_2_1_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</sub></font>, <font color="Maroon">c<sub>4</sub></font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>assume </b><a NAME="E1:4_2_1_1"/>
<font color="Maroon">c<sub>3</sub></font> <a href="rlvect_1.html#K2">+</a> <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>4</sub></font> <a href="rlvect_1.html#K2">+</a> <font color="Maroon">c<sub>2</sub></font>
 ;<br/><b>then </b><font color="Maroon">c<sub>2</sub></font> <a href="rlvect_1.html#K2">+</a> <font color="Maroon">c<sub>3</sub></font> = 
<font color="Maroon">c<sub>4</sub></font> <a href="rlvect_1.html#K2">+</a> <font color="Maroon">c<sub>2</sub></font>
<b>by </b><i><a class="txt" href="binom.html#E1:4_2_1"><i><font color="Green">E2</font></i></a>, <a class="ref" href="rlvect_1.html#D5">RLVECT_1:def 5</a></i>
<br/>.= 
<font color="Maroon">c<sub>2</sub></font> <a href="rlvect_1.html#K2">+</a> <font color="Maroon">c<sub>4</sub></font>
<b>by </b><i><a class="txt" href="binom.html#E1:4_2_1"><i><font color="Green">E2</font></i></a>, <a class="ref" href="rlvect_1.html#D5">RLVECT_1:def 5</a></i>
;<br/><b>hence </b><a NAME="E3:4_2_1_1"/>
<font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="binom.html#E1:4_2_1"><i><font color="Green">E2</font></i></a>, <a class="ref" href="algstr_1.html#D6">ALGSTR_1:def 6</a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E3:4_2_1"/>
<font color="Maroon">c<sub>1</sub></font> is <a href="algstr_1.html#V3">add-right-cancelable</a>
 <b>by </b><i><a class="ref" href="algstr_1.html#D7">ALGSTR_1:def 7</a></i>;<br/>


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