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<b>let </b><font color="Maroon" title="c1">X</font> be    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ;<br/><b>let </b><font color="Maroon" title="c2">f</font> be   <a href="funct_2.html#NM1" title="FUNCT_2:NM.1">Function</a> of <span class="p1"><a href="zfmisc_1.html#K2" title="ZFMISC_1:func.2">[:</a><span class="default"><font color="Maroon" title="c1">X</font>,<font color="Maroon" title="c1">X</font></span><a href="zfmisc_1.html#K2" title="ZFMISC_1:func.2">:]</a></span>, <a href="numbers.html#K1" title="NUMBERS:func.1">REAL</a> ;<br/>



<b>assume </b><a NAME="E1:13"/><i><font color="Green" title="E14">A1</font></i>: 
<font color="Maroon" title="c2">f</font> <a href="pcomps_1.html#R1" title="PCOMPS_1:pred.1">is_metric_of</a> <font color="Maroon" title="c1">X</font>
 ;<br/>

<a NAME="E2:13"/>
for <font color="Olive" title="b1">a</font>, <font color="Olive" title="b2">b</font>, <font color="Olive" title="b3">c</font> being   <a href="subset_1.html#M1" title="SUBSET_1:mode.1">Element</a> of <font color="Maroon" title="c1">X</font> holds <br/> ( <font color="Maroon" title="c2">f</font> <a href="metric_1.html#K1" title="METRIC_1:func.1">.</a> <font color="Olive" title="b1">a</font>,<font color="Olive" title="b1">a</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="numbers.html#K6" title="NUMBERS:func.6">0</a>  &amp; <font color="Maroon" title="c2">f</font> <a href="metric_1.html#K1" title="METRIC_1:func.1">.</a> <font color="Olive" title="b1">a</font>,<font color="Olive" title="b2">b</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c2">f</font> <a href="metric_1.html#K1" title="METRIC_1:func.1">.</a> <font color="Olive" title="b2">b</font>,<font color="Olive" title="b1">a</font> &amp; <font color="Maroon" title="c2">f</font> <a href="metric_1.html#K1" title="METRIC_1:func.1">.</a> <font color="Olive" title="b1">a</font>,<font color="Olive" title="b3">c</font> <a href="xxreal_0.html#R1" title="XXREAL_0:pred.1">&lt;=</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">f</font> <a href="metric_1.html#K1" title="METRIC_1:func.1">.</a> <font color="Olive" title="b1">a</font>,<font color="Olive" title="b2">b</font></span>)</span> <a href="real_1.html#K7" title="REAL_1:func.7">+</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">f</font> <a href="metric_1.html#K1" title="METRIC_1:func.1">.</a> <font color="Olive" title="b2">b</font>,<font color="Olive" title="b3">c</font></span>)</span> )
 
<b>by </b><i><a class="txt" href="nagata_2.html#E1:13"><i><font color="Green" title="E14">A1</font></i></a>, <a class="ref" href="pcomps_1.html#D7" title="PCOMPS_1:def.7">PCOMPS_1:def 7</a></i>;<br/>
<a NAME="E3:13"/><b>then </b>
( <font color="Maroon" title="c2">f</font> is <a href="metric_1.html#V2" title="METRIC_1:attr.2">Reflexive</a> &amp; <font color="Maroon" title="c2">f</font> is <a href="metric_1.html#V4" title="METRIC_1:attr.4">symmetric</a> &amp; <font color="Maroon" title="c2">f</font> is <a href="metric_1.html#V5" title="METRIC_1:attr.5">triangle</a> )
 
<b>by </b><i><a class="ref" href="metric_1.html#D3" title="METRIC_1:def.3">METRIC_1:def 3</a>, <a class="ref" href="metric_1.html#D5" title="METRIC_1:def.5">METRIC_1:def 5</a>, <a class="ref" href="metric_1.html#D6" title="METRIC_1:def.6">METRIC_1:def 6</a></i>;<br/>
<b>hence </b><a NAME="E4:13"/>
<font color="Maroon" title="c2">f</font> <a href="nagata_1.html#R1" title="NAGATA_1:pred.1">is_a_pseudometric_of</a> <font color="Maroon" title="c1">X</font>
 <b>by </b><i><a class="ref" href="nagata_1.html#D10" title="NAGATA_1:def.10">NAGATA_1:def 10</a></i>;<br/>


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