In mathematics,
-induction (epsilon-induction) is a variant of transfinite induction, which can be used in set theory to prove that all sets satisfy a given property P[x]. If the truth of the property for x follows from its truth for all elements of x, for every set x, then the property is true of all sets. In symbols:
This principle, sometimes called the axiom of induction (in set theory), is equivalent to the axiom of regularity.
-induction is a special case of well-founded induction.
The name is most often pronounced "epsilon-induction", because the set membership symbol
historically developed from the Greek letter ε.
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![\forall x (\forall y (y \in x \rightarrow P[y]) \rightarrow P[x]) \rightarrow \forall x P[x]](http://wpcontent.answers.com/math/6/8/5/6858e811a9e4bb7f02f83ef9a69c0443.png)



