# David Diamondstone

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bio website math.uchicago.edu/~ded location University of Chicago age 32 member for 5 years, 6 months seen Oct 24 '12 at 7:03 profile views 364
I am a graduate student studying mathematical logic. My research interests include computability theory and effective randomness.

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 Aug2 awarded Popular Question Dec26 awarded Popular Question Sep19 awarded Nice Question Jun9 awarded Yearling Jun9 awarded Nice Question Jun8 accepted Are there examples of nonconstructive metaproofs? Jun8 comment Are there examples of nonconstructive metaproofs? Great answer. But I would still be interested in more examples, if anyone has some more. Jun8 awarded Supporter Jun8 comment Are there examples of nonconstructive metaproofs? This can hardly be seen as a constructive proof, as the "constructive" part is entirely divorced from the "proof" part. Jun8 comment Are there examples of nonconstructive metaproofs? Isn't there a story where a famous mathematician was assigned an open problem as homework by a devious professor, and ended up solving it? Jun8 asked Are there examples of nonconstructive metaproofs? May16 comment Can Cantor set be the zero set of a continuous function? Each bump in the bump function has width 1/3^n. If the height is h(n), then the largest value of the kth derivative of of the stage n bumps will be 3^{kn}h(n) times the largest value of the kth derivative of the original bump function. If you want these to converge uniformly, the exact condition you need is that 3^{kn}h(n) converges to 0. So the necessary and sufficient condition on h to make the construction work is that for all a>0, h(n) is eventually less than a^n. So yes, 2^{-2^n} will work. May18 accepted Given n k-element subsets of n, is there a small subset A of n which intersects them all? May18 comment Given n k-element subsets of n, is there a small subset A of n which intersects them all? Thank you very much. May17 asked Given n k-element subsets of n, is there a small subset A of n which intersects them all? May6 awarded Fanatic Feb25 awarded Enthusiast Jan21 awarded Autobiographer Jan20 awarded Scholar Jan20 accepted Is there a computable model of ZFC?