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( not <font color="Maroon" title="c1">d</font> is  <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">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#K2" title="NAT_1:func.2">+</a> <a href="numbers.html#K6" title="NUMBERS:func.6">0</a>  )
 
<span class="kw">by</span> <span class="lab"><a class="ref" href="nat_1.html#T13" title="NAT_1:th.13">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="xboole_0.html#V1" title="XBOOLE_0:attr.1">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" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="Red">::  thesis: </font></span></a><span class="hide"> verum</span><br/>


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