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Harry Altman's user avatar
Harry Altman's user avatar
Harry Altman
  • Member for 14 years, 8 months
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Currently studying the complexity of natural numbers in various simple computational models, and also well partial orders and some other silly things with ordinals. And also some scattered other stuff. See website for more.

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68
What are the most attractive Turing undecidable problems in mathematics?
Apr 28, 2010
answer
43
Examples of common false beliefs in mathematics
May 14, 2016
answer
33
Examples of seemingly elementary problems that are hard to solve?
Sep 18, 2011
answer
30
Not especially famous, long-open problems which anyone can understand
Jul 26, 2012
answer
29
Axiomatic definition of integers
May 1, 2010
question
28
Are Minkowski sums of upward closed "convex" sets in $\mathbb{N}^k$ still "convex"? (WAS: Comparing mana costs in Magic: The Gathering)
Oct 18, 2017
question
25
Surreal exponentiation -- are the varying definitions equivalent? If not, is there agreement on which ones are better?
Feb 19, 2012
question
19
What if homotopy were expanded to allow any connected space instead of $[0,1]$?
May 2, 2015
question
19
What is the fairest order for stage-striking (and is it the Thue-Morse sequence)?
Nov 21, 2018
answer
18
Examples of common false beliefs in mathematics
Feb 6, 2011
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132
Continuity of the roots of a polynomial in terms of its coefficients
45
Are all $p$-adic number systems the same?
19
How to show $\ell^2_p$ not isometric to $\ell^2_{p'}$ unless $p\in\{1,2,\infty\}$?
17
Basic counterexample re: preimages of ideals
15
Is multiplication of games that are equivalent to numbers well-defined?