User:Dfeuer/Peano Axioms

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Axiom

NOTE: I am well aware that these are phrased differently from the ones in Main. We can resolve the differences later—nothing horrible here.

\((P_1)\)   $:$   $0$ is a natural number.      
\((P_2)\)   $:$   If $n$ is a natural number, so is $n^+$.      
\((P_3)\)   $:$   For any natural number $n$, $n^+ ≠ 0$.      
\((P_4)\)   $:$   For any natural numbers $m$ and $n$, if $m^+ = n^+$ then $m = n$      
\((P_5)\)   $:$   Principle of Mathematical Induction

For any set $A$, if the following conditions hold then $A$ contains every natural number:

$(1)\quad 0 \in A$
$(2)\quad$For every natural number $n$, $n \in A \implies n^+ \in A$.