# [FOM] Plea for literature on recursion theory in V_\omega

Francois G. Dorais dorais at math.cornell.edu
Wed Apr 30 17:21:29 EDT 2008

Vaughan Pratt wrote:
> What notations exist for the hereditarily countable sets?  I don't see
> an obvious extension of the above.
>
> Vaughan Pratt

See Gerald Sacks' "Higher Recursion Theory" where, in particular, he
develops a notation system for L_{\omega_1^{CK}}.

Another useful reference for the original poster would be Jon Barwise's