network profile
| bio | website | motls.blogspot.com |
|---|---|---|
| location | Czech Republic | |
| age | 39 | |
| visits | member for | 2 years |
| seen | 5 hours ago | |
| stats | profile views | 1,855 |
Hi, I am a string theorist and a publicist.
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Aug 17 |
awarded | Nice Answer |
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Jul 21 |
answered | IMO 2011 Problem 5 - Show that $f(m) \mid f(n)$ if $f(m) \leq f(n)$ |
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Jul 9 |
comment |
True, false, or meaningless? I see, so $\forall i\in \{\}: T(i)$ holds for any $T(i)$ because there is no counterexample in an empty set for which $T(i)$ would fail - it holds for everyone (all zero of them). On the other hand, $\exists i\in\{\}: T(i)$ is always untrue because there doesn't exist any $i$ in an empty set that has a property - whatever property - because there's nothing in an empty set even without adjectives. |
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Jul 9 |
answered | True, false, or meaningless? |
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Jul 9 |
answered | Closed-form Expression for $\sum_{j=0}^{k-1}(2j+2)\sum_{i=1}^j \frac 1 {i^2}$? (problem with Mathematica) |
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Jul 9 |
answered | Compositions of prime numbers |
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Jun 27 |
comment |
Validity of $\sum_{i=1}^n(a_i^2+b_i^2+c_i^2+d_i^2)\lambda_i\geq\lambda_1+\lambda_2+\lambda_3+\lambda_4$? Oh, I see, you're right. |
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Jun 27 |
comment |
Puzzle: $(\Box @)+(\Box @) = (\Box\bigstar\Box$) Thanks for your care and implicit compliments, @JTL and @Jyrki, but I don't think it's a big issue. Let's be generous, people have the right to vote the way they want. |
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Jun 27 |
awarded | Nice Answer |
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Jun 26 |
revised |
Validity of $\sum_{i=1}^n(a_i^2+b_i^2+c_i^2+d_i^2)\lambda_i\geq\lambda_1+\lambda_2+\lambda_3+\lambda_4$? added 99 characters in body; added 570 characters in body; added 2 characters in body |
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Jun 26 |
revised |
Puzzle: $(\Box @)+(\Box @) = (\Box\bigstar\Box$) added 123 characters in body |
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Jun 26 |
revised |
Validity of $\sum_{i=1}^n(a_i^2+b_i^2+c_i^2+d_i^2)\lambda_i\geq\lambda_1+\lambda_2+\lambda_3+\lambda_4$? added 454 characters in body; added 39 characters in body; added 55 characters in body; added 47 characters in body |
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Jun 26 |
comment |
Validity of $\sum_{i=1}^n(a_i^2+b_i^2+c_i^2+d_i^2)\lambda_i\geq\lambda_1+\lambda_2+\lambda_3+\lambda_4$? Interesting, I jumped on the same intuition as you did - it couldn't be right, I thought, because the RHS didn't have the minimal $\lambda$ anymore. Of course, the catch is that the "generalization" has almost nothing to do with the original inequality. |
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Jun 26 |
answered | Validity of $\sum_{i=1}^n(a_i^2+b_i^2+c_i^2+d_i^2)\lambda_i\geq\lambda_1+\lambda_2+\lambda_3+\lambda_4$? |
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Jun 26 |
comment |
How to take the inverse of this signal? You were faster, I erased my answer. ;-) |
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Jun 26 |
answered | Puzzle: $(\Box @)+(\Box @) = (\Box\bigstar\Box$) |
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Jun 26 |
answered | Eigenvectors of a normal matrix |
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Jun 26 |
answered | How common is the use of the term “primitive” to mean “antiderivative”? |
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Jun 26 |
comment |
Plane intersecting line segment The objects you called $dist$ are not distances in the exact sense. They're inner products which can be both positive and negative. There's no reason to divide the debate to the positive and negative case because all the geometrically natural formulae here are linear, rational, or otherwise analytic and they work uniformly both for positive and negative values of the inner products. |
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Jun 26 |
comment |
Plane intersecting line segment Dear @PUK, if a line belongs to a plane, then it surely is parallel with it. At any rate, when it is so, the intersection - as in set theory - of the plane and the line is the whole line (the very same one). I don't understand in what sense it would make sense to pick two particular points on the line as "better intersections" than all the other points. Also, I am confused by your separate discussion of negative and positive values of $dist.dist$. A fun about maths and algebra is that one may calculate with negative numbers just like with the positive ones w/o splitting derivations. |
