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<a NAME="E1:6_1_1"/>
(  not <font color="Maroon" title="c1">d</font> is  <a href="ordinal1.html#V8" title="ORDINAL1:attr.8">zero</a>  iff <font color="Maroon" title="c1">d</font> <a href="xxreal_0.html#NR2" title="XXREAL_0:NR.2">&gt;=</a> 1 <a href="nat_1.html#K1" title="NAT_1:func.1">+</a> <a href="numbers.html#K5" title="NUMBERS:func.5">0</a> )
 
<span class="kw">by</span> <span class="lab"><a class="ref" href="nat_1.html#T13" onmouseover="rs('nat_1/T13')" onmouseout="rh()">NAT_1:13</a></span>;<br/>
<span class="kw">hence </span><a NAME="E2:6_1_1"/>
( <font color="Maroon" title="c1">d</font> is  <a href="ordinal1.html#V8" title="ORDINAL1:attr.8">zero</a>  iff  not <font color="Maroon" title="c1">d</font> <a href="xxreal_0.html#NR2" title="XXREAL_0:NR.2">&gt;=</a> 1 )
 ; <a class="txt" onmouseover="tooltip.show('hs',this)" onmouseout="tooltip.hide()" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="firebrick">::  thesis: </font></span></a><span class="hide"> verum</span><br/>


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