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3 votes
0 answers
283 views

What is the meaning and proof of Harvey Friedman’s ultrafinite incompleteness sentence?

On page 7 of his paper “Adventures in Incompleteness”, Harvey Friedman states the following: IN ANY LONG ENOUGH SEQUENCE $x_1,...,x_n$ FROM $\{1,2,3\}$, SOME $(x_i,...,x_{2i})$ IS A SUBSEQUENCE OF ...
Keshav Srinivasan's user avatar
12 votes
2 answers
868 views

The inconsistency of Graham Arithmetics plus $ \forall n, n < g_{64}$

As you all know, Ronald Graham just passed away. He is famous for many fabulous contributions to finite combinatorics, and much much more, but perhaps none of them is as popular as the infamous ...
Mirco A. Mannucci's user avatar