[FOM] Role of Polemics

Lew Gordeew legor at gmx.de
Sun Jan 22 19:54:22 EST 2006

Harvey Friedman wrote on Sat, 21 Jan 2006:
> E.g., there is Igor Kriz's extension of my EKT. The Kriz proof uses
> something like light faced Pi12-CA0, if I recall. We have no idea how
> strong Kriz's extension of my EKT is, at this point.

If you mean Kriz's "Well quasiordering finite trees with gap conditions
...", then it is just as strong as my extension of your EKT. Namely, I
proved that both ordinal-labeled extensions have the strength of Pi11
transfinite recursion axiom with the restricted induction (this formal
system is defined like ATR0 modulo Pi11 transfinite recursion). This result
was presented at the Fourteenth British Combinatorial Conference in Keele
(1993), see full

L. Gordeev

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