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"If he had been a great and wise philosopher... he would now have comprehended that Work consists of whatever a body is obliged to do, and that Play consists of whatever a body is not obliged to do. And this would help him to understand why constructing artificial flowers or performing on a tread-mill is work, while rolling ten-pins or climbing Mont Blanc is only amusement."

-- from The Adventures of Tom Sawyer by Mark Twain --


4h
reviewed Reject Inequality about moments of a random variable and of its conditional expectation
14h
revised Why do dynamicists worry so much about differentiability hypotheses in smooth dynamics?
removed tag I feel was unnecessary and inappropriate
14h
comment Why do dynamicists worry so much about differentiability hypotheses in smooth dynamics?
I have removed the tag "math-philosophy" which I do not think is appropriate here: or if it is appropriate here, it should be added to so many questions that it loses its meaning
14h
comment What does the Plancherel theorem say about positive-definite distributions?
First comment straight out of the box: the Plancherel formula (in its usual interpretation) does not hold for all locally compact groups, you usually need something like the asssumption of the group being Type I. Non-abelian free groups are not Type I; neither is the integer Heisenberg group; but connected semisimple Lie groups are, and probably loads of groups the number theorists care about (e.g. ${\rm GL}(n,{\bf Q}_p)$) are also Type I
1d
comment Is Zsigmondy's Theorem utilized in Sociology to the extent that a lay person might be familiar with its use?
Why do you think it is Karl Zsigmondy, as opposed to, say, the chemist or the dentist?
1d
comment Irreducible unitary representations of semidirect groups of a discrete abelian group by a discrete group
It might be OK in this setting, I just occasionally get worried about induction versus co-induction. There are definitely problems for locally compact, non-discrete groups though
1d
comment Irreducible unitary representations of semidirect groups of a discrete abelian group by a discrete group
Since these groups may be infinite, is Frobenius reciprocity still directly applicable?
2d
reviewed Leave Open Which journals publish research announcements?
Jul
4
comment Uniformly small sums of roots of unity
Just to clarify: do you mean that for each such $k$ there exists an $S$ of cardinality $k$, etc?
Jul
4
comment HISTORY OF MATHEMATICS
@JohnStillwell +1000 if I could
Jul
4
reviewed Reject Bijection between dominant rational maps and morphisms of function fields?
Jul
1
comment A question on an argument in Woronowicz’s paper on the compact quantum group $ {\text{SU}_{q}}(2) $
[deleted comment caused by not reading properly; sorry]
Jul
1
comment Question on real polynomial in projective space
I'm voting to close this question for the reason in my previous comment
Jul
1
comment Question on real polynomial in projective space
I don't think MO should be a substitute for the process of graduate instruction
Jul
1
revised Can phase significantly concentrate a function's spectrum?
deleted 81 characters in body
Jul
1
comment Can phase significantly concentrate a function's spectrum?
@WillSawin Good point. I'll update my answer
Jun
30
answered Can phase significantly concentrate a function's spectrum?
Jun
29
comment 'Test Functions' to Lower Bound the Norm of Elements of Dual Quantum Group
OK, I've cobbled something together. Apologies for any earlier confusion
Jun
29
answered 'Test Functions' to Lower Bound the Norm of Elements of Dual Quantum Group
Jun
28
comment 'Test Functions' to Lower Bound the Norm of Elements of Dual Quantum Group
Correction to my earlier comment: while this result is in Dixmier's book, the "Section V.2" actually refers to Volume 1 of Takesaki's Theory of Operator Algebras