# The Feferman-Schütte ordinal, $\Gamma_0$

The Feferman-Schütte ordinal, denoted $\Gamma_0$ ("gamma naught"), is the first ordinal fixed point of the $\Gamma$ function, defined via the Veblen function. It figures prominently in the ordinal-analysis of the proof-theoretic strength of several mathematical theories.

## Veblen hiearchy

Definition needed

## Gamma function

Definition needed

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