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<b>let </b><font color="Maroon">IT</font> be  non <a href="struct_0.html#V3">empty</a>  <a href="group_1.html#L1" target="_self">HGrStr</a> ;<br/>

<b>assume </b><a NAME="E1:7_1_1"/>
 ex <font color="Olive">e</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">IT</font> st <br/>for <font color="Olive">h</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">IT</font> holds <br/> ( <font color="Olive">h</font> <a href="group_1.html#K1" target="_self">*</a> <font color="Olive">e</font> <a href="hidden.html#R1">=</a> <font color="Olive">h</font> &amp; <font color="Olive">e</font> <a href="group_1.html#K1" target="_self">*</a> <font color="Olive">h</font> <a href="hidden.html#R1">=</a> <font color="Olive">h</font> &amp;  ex <font color="Olive">g</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">IT</font> st <br/>( <font color="Olive">h</font> <a href="group_1.html#K1" target="_self">*</a> <font color="Olive">g</font> <a href="hidden.html#R1">=</a> <font color="Olive">e</font> &amp; <font color="Olive">g</font> <a href="group_1.html#K1" target="_self">*</a> <font color="Olive">h</font> <a href="hidden.html#R1">=</a> <font color="Olive">e</font> ) )
 ; <i><font color="Red">:: according to </font></i><a class="ref" href="group_1.html#D3" target="_self">GROUP_1:def 3</a><br/>

<b>hence </b><a NAME="E2:7_1_1"/>
 ex <font color="Olive">e</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">IT</font> st <br/>for <font color="Olive">h</font> being  <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">IT</font> holds <br/> ( <font color="Olive">h</font> <a href="group_1.html#K1" target="_self">*</a> <font color="Olive">e</font> <a href="hidden.html#R1">=</a> <font color="Olive">h</font> &amp; <font color="Olive">e</font> <a href="group_1.html#K1" target="_self">*</a> <font color="Olive">h</font> <a href="hidden.html#R1">=</a> <font color="Olive">h</font> )
 ; <i><font color="Red">:: according to </font></i><a class="ref" href="group_1.html#D2" target="_self">GROUP_1:def 2</a><br/>


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