10,383 reputation
33171
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location Moscow, Russia
age
visits member for 4 years, 4 months
seen 16 hours ago

umagon at google mail


Jul
15
reviewed Close Sketch $y=2x^3/(x^2-2)$
Jul
15
reviewed No Action Needed Explaining Infinite Sets and The Fault in Our Stars
Jul
15
reviewed Leave Closed Why is $\;n^2-\frac{n^2}{2} =\frac{n^2}{2}\;$?
Jul
15
comment How to compute homotopy classes of maps on the 2-torus?
@Qiaochu Let's see. In the same spirit for $D^2$ we have 'a' trivial element of $\pi_1$ and an element of $\pi_2$ up to some equivalence relation; and in the part 'Let's see if this element of $\pi_2$ is well-defined' we have $s'=s+t$ — i.e. equivalence relation identifies all elements of $\pi_2$. That's the correct answer.
Jul
14
reviewed Close Show that the semigroup S(t) here described is a contraction semigroup
Jul
14
revised if each each of two natural numbers a and b is a sum of two squares then ab is also a sum of two squares
more descriptive title
Jul
14
reviewed No Action Needed Polar form of (univariate) polynomials: looking for a proof
Jul
13
reviewed Reviewed Mellin transform of a shifted function
Jul
13
reviewed No Action Needed Matrix chain product
Jul
13
reviewed No Action Needed Long exact sequence of a fibration, center
Jul
13
reviewed Leave Closed Identity with binomials
Jul
13
reviewed Reject suggested edit on Teaching children to convert between number bases
Jul
13
reviewed Looks OK How to calculate integral $\int_{0}^{s}\frac{1+x^{a+1}}{x^a}dx$
Jul
13
reviewed Looks OK Does every “balloon” (dragon, tadpole, canoe paddle) admit a graceful labeling?
Jul
13
reviewed Leave Open Power series convergence radius
Jul
13
reviewed Looks OK Infinitely many prime $n$ for which $n^2 = p + 8$ for some prime $p$.
Jul
13
reviewed Leave Closed I want to study Numerical linear algebra
Jul
13
reviewed Close limit of a sum of powers of integers
Jul
13
reviewed No Action Needed Solve for an article's time constant given three internal temperatures and their times.
Jul
12
reviewed Close How to prove validity of following sequent