Difference between revisions of "Induction proof"

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imported>Christophe
imported>Christophe
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<math>\forall i. i \in \mathbb{N}  \Rightarrow P(i+1)</math>
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<math>\forall i. i \in \mathbb{N}  \Rightarrow P(i)</math>
  
 
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Revision as of 21:24, 13 October 2008

This page explains how to proove with induction method on the natural number with Rodin tools. In other words, how to proove :

P(0)

\forall i.i \in \mathbb{N}\land P(i) \Rightarrow P(i+1)

\vdash
\forall i. i \in \mathbb{N}  \Rightarrow P(i)


The proof key is the following theorem:

\forall s.s \subseteq \mathbb{N} \land 0 \in s \land  (\forall n.n \in s => n+1 \in s)\Rightarrow  N \subseteq s


The proof of the previous theorem is given by instanciate the key theorem with : 	  \{x|x\in \mathbb{N} \land P(x)\}