<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon" title="c1">T</font> be   <a href="trees_1.html#NM1" title="TREES_1:NM.1">Tree</a>;<br/><b>let </b><font color="Maroon" title="c2">t1</font>, <font color="Maroon" title="c3">t2</font> be    <a href="trees_1.html#M1" title="TREES_1:mode.1">Element</a> of <font color="Maroon" title="c1">T</font>;<br/>





<b>assume </b><a NAME="E1:63"/>
not <font color="Maroon" title="c2">t1</font>,<font color="Maroon" title="c3">t2</font> <a href="xboole_0.html#R3" title="XBOOLE_0:pred.3">are_c=-comparable</a> 
 ;<br/>

<b>then reconsider </b><font color="Maroon" title="c4">A</font> = <span class="p1"><a href="tarski.html#K2" title="TARSKI:func.2">{</a><span class="default"><font color="Maroon" title="c2">t1</font>,<font color="Maroon" title="c3">t2</font></span><a href="tarski.html#K2" title="TARSKI:func.2">}</a></span> as   <a href="trees_1.html#NM5" title="TREES_1:NM.5">AntiChain_of_Prefixes</a> <b>by </b><i><a class="ref" href="trees_1.html#T71" target="_self" title="TREES_1:th.71">Th71</a></i>;<br/>
<a NAME="E3:63"/>
<font color="Maroon" title="c4">A</font> is    <a href="trees_1.html#M4" title="TREES_1:mode.4">AntiChain_of_Prefixes</a> of <font color="Maroon" title="c1">T</font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="63_1"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon" title="c5">x</font> be    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="tarski.html#D3" title="TARSKI:def.3">TARSKI:def 3</a>,<a class="ref" href="trees_1.html#D14" target="_self" title="TREES_1:def.14">TREES_1:def 14</a><br/>

<b>assume </b><a NAME="E1:63_1"/>
<font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c4">A</font>
 ;<br/>

<a NAME="E2:63_1"/><b>then </b>
( <font color="Maroon" title="c5">x</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">t1</font> or <font color="Maroon" title="c5">x</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c3">t2</font> )
 
<b>by </b><i><a class="ref" href="tarski.html#D2" title="TARSKI:def.2">TARSKI:def 2</a></i>;<br/>
<b>hence </b><a NAME="E3:63_1"/>
<font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c1">T</font>
 ;<br/>


</div><b>end;</b></div>
<b>hence </b><a NAME="E4:63"/>
<span class="p1"><a href="tarski.html#K2" title="TARSKI:func.2">{</a><span class="default"><font color="Maroon" title="c2">t1</font>,<font color="Maroon" title="c3">t2</font></span><a href="tarski.html#K2" title="TARSKI:func.2">}</a></span> is    <a href="trees_1.html#M4" title="TREES_1:mode.4">AntiChain_of_Prefixes</a> of <font color="Maroon" title="c1">T</font>
 ;<br/>


</div>
