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10h
comment Is it easier to determine that a matrix is singular than it is to determine nonsingular?
@SeethaRamaRajuSanapala You're right that in the worst case, they require the same amount of work to determine. But in the best case, singular is easier because you might stumble upon the necessary $v$ right away, and then you don't have to do any more work.
10h
answered Is it easier to determine that a matrix is singular than it is to determine nonsingular?
2d
answered What does the function domain with letter C stand for?
Apr
23
answered Intuition for integrating $1/z$ around the unit circle
Apr
21
comment Is the language of complex numbers regular?
If you want matched parentheses, then James' answer seems relevant.
Apr
21
comment Is the language of complex numbers regular?
Okay, but then, do you want to represent "sqrt(2)" as a sequence of 7 Latin characters, "s" followed by "q" followed by... Or maybe you want to represent every real number as an atomic symbol in the alphabet of your language?
Apr
21
comment Is the language of complex numbers regular?
Well, it's probably a good question, but it needs details to be answered definitively. If we're going by Peter Linz's book "An Introduction to Formal Languages and Automata", it seems that whenever he talks about "real numbers", he specifically means numerical constants in the C programming language. These include "1.23" and "-4" but not "sqrt(2)" or "0.333...". Of course, you're free to mean something different by "real numbers", possibly including "sqrt(2)". It would be good to specify what that language is, in the question.
Apr
21
comment Is the language of complex numbers regular?
Where did this question come from, and are there any further details? In particular, is a language for real numbers given? Remember that most real numbers do not have finite representations...
Apr
20
comment Toffoli gate cannot be decomposed into a sequence of one or two classical bits gates
math.stackexchange.com/help/privileges/set-bounties "How do I award the bounty? You can award a bounty by clicking on the respective button below the upvote/downvote interface. ... You can accept an answer without awarding a bounty to it."
Apr
14
accepted Does $A_n$ split a complement of the stabilizer of a partition of $[n]$?
Apr
14
comment Why do division algebras always have a number of dimensions which is a power of $2$?
The original statement of this fact is from Hopf, Heinz. "Ein topologischer Beitrag zur reellen Algebra." Commentarii mathematici Helvetici 13 (1940/41): 219-239. See Satz IV: gdz.sub.uni-goettingen.de/dms/load/img/… or digizeitschriften.de/dms/img/…
Apr
12
answered What is the number of $n \times n$ binary matrices $A$ such that $\det(A) = \text{perm}(A)$?
Apr
12
comment What is the number of $n \times n$ binary matrices $A$ such that $\det(A) = \text{perm}(A)$?
With the above improvements plus dynamic programming to reduce the effort of tracking permutations, I got a(7) down to 0.3 seconds, and $a(8)=1282759836215548737$ in a few minutes! Updated Github. At the current complexity, with some changes to handle numbers greater than 64 bits, a(9) should take less than a day. I might take a break from doing that, though, and write up what I've done so far in an answer.
Apr
11
asked Does $A_n$ split a complement of the stabilizer of a partition of $[n]$?
Apr
11
answered Does $A_n$ split a complement of the stabilizer of a partition of $[n]$?
Apr
9
comment Get curvature and torsion of a curve represented with a amount of points
Try Theorems 2.3 and (2.5 or 2.6) in: Langer, Torsten, Alexander G. Belyaev, and Hans-Peter Seidel. "Asymptotic analysis of discrete normals and curvatures of polylines." Proceedings of the 21st spring conference on Computer graphics. ACM, 2005.
Apr
9
comment Is it possible to interchange order of supremum and supremum?
Instead of proving your equation $x=y$ in a single stroke, can you prove $x\leq y$?
Apr
8
answered Number system with $e^x = 0$ for some $x$
Apr
6
answered Which function grows at a faster rate? $n!$ or $2^{n^2}$
Apr
5
comment Two convergent series, Cauchy Product
In the hint, are you sure you got the capitalization of the variable names right? That part looks suspicious.