Révision 215

CSL17/arithmetic.tex (revision 215)
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Let us give a few examples of formulas representing basic functions.
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\begin{itemize}
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\item Successor $\succ{}$: $\forall^{\safe} x, \exists^{\safe} y. y=x+1.$
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\item Projection $\pi_k^{m,n}$: $\forall^{\normal} u_1, \dots, u_m,  \forall^{\safe} x_{m+1}, \dots, x_{m+n}, \exists^{\safe} y. y=x_k$.
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\item Successor $\succ{}$: $\forall^{\safe} x, \exists^{\safe} y. y=x+1.$. The formulas for the binary successors $\succ{0}$, $\succ{1}$ and the constant functions $\epsilon^k$ are defined in a similar way.
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\item Predecessor $p$:   $\forall^{\safe} x, \exists^{\safe} y. (x=\succ{0} y \cor x=\succ{1} y \cor (x=\epsilon \cand y= \epsilon)) .$
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\item Conditional $C$:
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$$\begin{array}{ll}
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\forall^{\safe} x, y_{\epsilon}, y_0, y_1, \exists^{\safe} y. & ((x=\epsilon)\cand (y=y_{\epsilon})\\
......
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\end{array}
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$$
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\end{itemize}
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\patrick{to be continued}
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\subsection{Encoding sequences in the arithmetic}


  		





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\todo{}


  		





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