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<b>set </b><font color="Maroon">c<sub>1</sub></font> =  <a href="trees_1.html#K2" target="_self">elementary_tree</a> 0;<br/>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="72_1"><b>now </b></a><div class="add"><b>reconsider </b><font color="Maroon">c<sub>2</sub></font> = <span class="p1"><a href="tarski.html#K1">{</a><span class="default"><a href="xboole_0.html#K1">{}</a> </span><a href="tarski.html#K1">}</a></span> as    <a href="trees_1.html#M4" target="_self">AntiChain_of_Prefixes</a> of  <a href="trees_1.html#K2" target="_self">elementary_tree</a> 0 <b>by </b><i><a class="ref" href="trees_1.html#T73" target="_self">Th73</a></i>;<br/><b>take </b><font color="Maroon">c<sub>3</sub></font> = <font color="Maroon">c<sub>2</sub></font>;<br/><b>thus </b><a NAME="E2:72_1"/>
1 <a href="hidden.html#R1">=</a>  <a href="card_1.html#K4">card</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="ref" href="card_1.html#T79">CARD_1:79</a></i>;<br/><b>let </b><font color="Maroon">c<sub>4</sub></font> be    <a href="trees_1.html#M4" target="_self">AntiChain_of_Prefixes</a> of  <a href="trees_1.html#K2" target="_self">elementary_tree</a> 0;<br/><a NAME="E3:72_1"/>
<font color="Maroon">c<sub>4</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="ref" href="trees_1.html#D14" target="_self">Def14</a>, <a class="ref" href="trees_1.html#T56" target="_self">Th56</a></i>;<br/><b>hence </b><a NAME="E4:72_1"/>
 <a href="card_1.html#K4">card</a> <font color="Maroon">c<sub>4</sub></font> <a href="xxreal_0.html#R1">&lt;=</a>  <a href="card_1.html#K4">card</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="ref" href="card_1.html#T80">CARD_1:80</a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E2:72"/>
 <a href="trees_1.html#K7" target="_self">width</a> <span class="p1">(<span class="default"><a href="trees_1.html#K2" target="_self">elementary_tree</a> 0</span>)</span> <a href="hidden.html#R1">=</a> 1
 <b>by </b><i><a class="ref" href="trees_1.html#D16" target="_self">Def16</a></i>;<br/>


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