FOM: Nonstandard models of N

Dave Marker marker at
Thu Mar 15 11:14:08 EST 2001

Another positive result is obtained by combining a Henkin argument
with the Jockusch-Soare low basis theorem to produce a low
nonstandard model of arithmetic (i.e. the jumps of + and * are only

The result that there is no arithmetic nonstandard model of true
arithmetic is due to Feferman.

I believe that Julia Knight has a survey article on this subject in
the recently published Handbook of Computability Theory.

Dave Marker

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