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Daniel Asimov's user avatar
Daniel Asimov's user avatar
Daniel Asimov's user avatar
Daniel Asimov
  • Member for 14 years, 9 months
  • Last seen this week
  • University of California, Berkeley
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Homomorphism from field of hyperreals to field of reals?
I believe that in order for this question to be clear, the OP should provide the exact definition of "hyperreals" that is being used in the question.
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Homology with Coefficients
Nothing in the question hints at any object that has "faces".
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Curl-Div equation with singular matrix
You make no mention of x other than to state that it is a member of š›€. It would help me understand the question if you clearly distinguished between what is the unknown that you are trying to solve for, and what is given.
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What is the best way to read advanced textbooks in Pure Mathematics (PhD Level)?
Yes, always read actively. With a pen or pencil and a pad of paper, so you can try to check anything in the book that seems less than obvious. Also, look ahead and at the table of contents, so you have an idea of where you've been and where you are going.
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Is there a sparse almost disjoint family over $\omega$ of cardinality $2^{\aleph_0}$?
It's much better to let the OP answer such a question, especially since the linked article has multiple definitions for "almost disjoint".
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What are some reasonable-sounding statements that are independent of ZFC?
Have people considered adding "šœ… < šœ† ā‡’ 2^šœ… < 2^šœ† as a axiom extending ZFC ?
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'Uniformity' of surfaces of 3D convex solids
Do you mean "minimum" where you write "max value" ?
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How many unit cubes are needed to 'hide' a unit cube fully in 3D?
Can we assume that the word "nonoverlapping" here means precisely that the interiors have empty intersection?
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The unproved formulas of Ramanujan
infinity —> infinitely
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The unproved formulas of Ramanujan
I have not read previous comments, but: The question of proving that "N^x is an integer for all positive integers N" implies "x is an integer" was on an old Putnam exam, probably in the early '70s. The suggested solution made use of only this fact for N āˆˆ {2,3}, just as does the purported unsolved Ramanujan problem. I don't know if Ramanujan thought about this problem or not, but it definitely has been solved. Let me add, one the hardest Putnam problems anyone could remember. I don't recall whether anyone solved it during the exam.
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What's the lowest-dimensional Euclidean space in which a hexagonal 2-torus smoothly embeds isometrically?
Namely, Hopf tori in S^3, Ulrich Pinkall, Inventiones Mathematicae, v. 81, 1985.
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What's the lowest-dimensional Euclidean space in which a hexagonal 2-torus smoothly embeds isometrically?
Ian ā€” I had thought that result applied to conformally equivalent Riemann surfaces (rather than isometry classes up to scaling).
awarded
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On the global, smooth isometric embedding of a torus into $\mathbb{R}^3$
When you mention "the flat torus", which of the infinitely many conformally inequivalent flat tori does this refer to?
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Is there a $W^{2,2}$ isometric embedding of the flat torus into $\mathbb{R}^3$?
There is no such thing as the flat torus. There are uncountably many distinct flat tori that are not mutually conformally equivalent. (The flat torus that has been C^1 isometrically embedded in 3-space explicitly is a square torus.)
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