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 <a href="pre_ff.html#K3">Fib</a> 4 = 
 <a href="pre_ff.html#K3">Fib</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default">2 <a href="nat_1.html#K1">+</a> 1</span>)</span> <a href="nat_1.html#K1">+</a> 1</span>)</span>

<br/>.= 
3
<b>by </b><i><a class="ref" href="fib_num2.html#T23" target="_self">Th23</a>, <a class="ref" href="fib_num2.html#T24" target="_self">Th24</a>, <a class="ref" href="pre_ff.html#T1">PRE_FF:1</a></i>
;<br/>
<b>hence </b><a NAME="E2:36"/>
 <a href="pre_ff.html#K3">Fib</a> 4 <a href="hidden.html#R1">=</a> 3
 ;<br/>


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