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<div class="add">

<b>let </b><font color="Maroon">G1</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/><b>let </b><font color="Maroon">G2</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/><b>let </b><font color="Maroon">H1</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/><b>let </b><font color="Maroon">H2</font> be   <a href="zf_lang.html#NM2">ZF-formula</a>;<br/><b>let </b><font color="Maroon">x</font> be   <a href="zf_lang.html#NM1">Variable</a>;<br/><b>let </b><font color="Maroon">y</font> be   <a href="zf_lang.html#NM1">Variable</a>;<br/>











<b>thus </b><a NAME="E1:158"/>
( <font color="Maroon">G1</font> <a href="zf_lang.html#K7">'&amp;'</a> <font color="Maroon">G2</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">H1</font> <a href="zf_lang.html#K7">'&amp;'</a> <font color="Maroon">H2</font></span>)</span> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> implies ( <font color="Maroon">G1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">H1</font> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> &amp; <font color="Maroon">G2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">H2</font> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> ) )
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="158_1"><b>proof </b></a><div class="add">

<b>assume </b><a NAME="E1:158_1"/>
<font color="Maroon">G1</font> <a href="zf_lang.html#K7">'&amp;'</a> <font color="Maroon">G2</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">H1</font> <a href="zf_lang.html#K7">'&amp;'</a> <font color="Maroon">H2</font></span>)</span> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font>
 ;<br/>

<a NAME="E2:158_1"/><b>then </b>
<font color="Maroon">G1</font> <a href="zf_lang.html#K7">'&amp;'</a> <font color="Maroon">G2</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">H1</font> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font></span>)</span> <a href="zf_lang.html#K7">'&amp;'</a> <span class="p1">(<span class="default"><font color="Maroon">H2</font> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font></span>)</span>
 
<b>by </b><i><a class="ref" href="zf_lang1.html#T67" target="_self">Th67</a></i>;<br/>
<b>hence </b><a NAME="E3:158_1"/>
( <font color="Maroon">G1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">H1</font> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> &amp; <font color="Maroon">G2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">H2</font> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> )
 <b>by </b><i><a class="ref" href="zf_lang.html#T47">ZF_LANG:47</a></i>;<br/>


</div><b>end;</b></div>

<b>thus </b><a NAME="E2:158"/>
( <font color="Maroon">G1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">H1</font> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> &amp; <font color="Maroon">G2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">H2</font> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> implies <font color="Maroon">G1</font> <a href="zf_lang.html#K7">'&amp;'</a> <font color="Maroon">G2</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">H1</font> <a href="zf_lang.html#K7">'&amp;'</a> <font color="Maroon">H2</font></span>)</span> <a href="zf_lang1.html#K6" target="_self">/</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> )
 <b>by </b><i><a class="ref" href="zf_lang1.html#T67" target="_self">Th67</a></i>;<br/>


</div>
