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Accepted answer and score of 40 or more. This badge can be awarded multiple times.

Awarded 2678 times.

Evaluation of a product of sines

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marlu

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Integrating a Partial Derivative

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Glen O

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Geometrically, why do line bundles have inverses with respect to the tensor product?

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Ted Shifrin

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Is every group the automorphism group of a group?

Awarded Mar 18 at 20:51

user1729

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Explain proof that any positive definite matrix is invertible

Awarded Mar 18 at 1:16

AlexR

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Is it possible to elementarily parametrize a circle without using trigonometric functions?

Awarded Mar 17 at 3:41

H. H. Rugh

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Why isn't the derivative of the volume of the cone its surface area?

Awarded Mar 15 at 4:09

Karl

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Does every infinite field contain a countably infinite subfield?

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David C. Ullrich

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Can every irrational number be written in terms of finitely many rational numbers?

Awarded Mar 11 at 18:09

Will Jagy

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How do you rotate a vector by a unit quaternion?

Awarded Mar 8 at 18:41

Will Jagy

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Expected Value of Max of IID Variables

Awarded Mar 8 at 17:15

smanoos

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Gram matrix invertible iff set of vectors linearly independent

Awarded Mar 4 at 14:06

Ryo

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Understanding the difference between Span and Basis

Awarded Feb 27 at 9:33

KittyL

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Infinite series $\sum _{n=2}^{\infty } \frac{1}{n \log (n)}$

Awarded Feb 27 at 4:33

Julien Clancy

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Find the sum of $\sum \frac{1}{k^2 - a^2}$ when $0<a<1$

Awarded Feb 24 at 0:33

J. M. ain't a mathematician

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Understanding the definition of nowhere dense sets in Abbott's Understanding Analysis

Awarded Feb 23 at 19:41

John Colanduoni

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How to transform a general higher degree five or higher equation to normal form?

Awarded Feb 23 at 18:20

Tito Piezas III

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Trace of an Inverse Matrix

Awarded Feb 19 at 21:25

Girish

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Why is (co)homology useful and in which way?

Awarded Feb 17 at 21:27

HallaSurvivor

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Sheaf cohomology: what is it and where can I learn it?

Awarded Feb 17 at 3:47

Akhil Mathew

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showing that $n$th cyclotomic polynomial $\Phi_n(x)$ is irreducible over $\mathbb{Q}$

Awarded Feb 15 at 10:04

Paramanand Singh♦

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Upper limit of summation index lower than lower limit?

Awarded Feb 14 at 16:09

Arturo Magidin

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Why don't we use closed covers to define compactness of metric space?

Awarded Feb 13 at 0:43

MJD

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How does Dummit and Foote's abstract algebra text compare to others?

Awarded Feb 12 at 20:04

bfhaha

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Closure of the union = Union of closures

Awarded Feb 9 at 21:01

Hermès

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Dual of $l^\infty$ is not $l^1$

Awarded Feb 2 at 10:34

martini

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Is the empty graph connected?

Awarded Feb 1 at 1:28

Qiaochu Yuan

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1 to the power of infinity, why is it indeterminate?

Awarded Jan 28 at 3:10

Brian M. Scott

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What is a blow-up?

Awarded Jan 27 at 16:48

Andrew

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Is connectedness $\implies $ local connectedness?

Awarded Jan 23 at 21:55

Ross Millikan

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Difference between power law distribution and exponential decay

Awarded Jan 22 at 15:02

Michael Hardy

Difference between topology and sigma-algebra axioms.

Awarded Jan 21 at 10:12

memeplex

5165 silver badges4 bronze badges

Reverse mode differentiation vs. forward mode differentiation - where are the benefits?

Awarded Jan 20 at 11:34

user664303

6527 silver badges8 bronze badges

Difference between weak ( or martingale ) and strong solutions to SDEs

Awarded Jan 17 at 0:32

saz

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Can all circles of radius $1/n$ be packed in a unit disk, excluding the circle of radius $1/1$?

Awarded Jan 14 at 19:27

Oleg567

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Can "Taking algebraic closure" be made into a functor?

Awarded Jan 13 at 12:05

Eric Wofsey

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Arithmetic mean. Why does it work?

Awarded Jan 10 at 4:57

mweiss

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Proof of Floyd Cycle Chasing (Tortoise and Hare)

Awarded Jan 7 at 8:19

paw88789

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"Negative" versus "Minus"

Awarded Jan 6 at 11:42

rschwieb

146k15 gold badges156 silver badges378 bronze badges

Hölder's inequality with three functions

Awarded Jan 5 at 15:35

user14242

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Dantzig's unsolved homework problems

Awarded Dec 28, 2022 at 22:20

Gerry Myerson

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Bijection between ideals of $R/I$ and ideals containing $I$

Awarded Dec 28, 2022 at 0:55

Arturo Magidin

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The graph of xy = 1 is connected or not

Awarded Dec 23, 2022 at 14:50

Per Erik Manne

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Is the intersection of a closed set and a compact set always compact?

Awarded Dec 23, 2022 at 11:05

Matt E

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Regular average calculated accumulatively

Awarded Dec 22, 2022 at 14:35

Chris Taylor

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I don't get the relationship between differentials, differential forms, and exterior derivatives.

Awarded Dec 17, 2022 at 13:16

Jack Lee

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What is $(26+15(3)^{1/2})^{1/3}+(26-15(3)^{1/2})^{1/3}$?

Awarded Dec 14, 2022 at 17:06

Vladimir Reshetnikov

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Totally bounded, complete $\implies$ compact

Awarded Dec 14, 2022 at 13:41

Brian M. Scott

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Historical Mistake of Assuming Measurability

Awarded Dec 13, 2022 at 8:30

Yuval Peres

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Why do I get a converging result when pressing cosine multiple times on a calculator?

Awarded Dec 10, 2022 at 18:03

Xander Henderson♦

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What is the norm of a complex number?

Awarded Dec 8, 2022 at 21:36

Marc van Leeuwen

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when can we interchange integration and differentiation

Awarded Dec 8, 2022 at 7:42

Eric Towers

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What is a limit point

Awarded Dec 7, 2022 at 14:17

Denis

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How many irreducible polynomials of degree $n$ exist over $\mathbb{F}_p$?

Awarded Dec 3, 2022 at 15:56

Qiaochu Yuan

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Is there a function with a removable discontinuity at every point?

Awarded Dec 2, 2022 at 6:30

Aryabhata

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How are norms different from absolute values?

Awarded Nov 29, 2022 at 22:38

Arturo Magidin

374k55 gold badges778 silver badges1098 bronze badges

Why do single-author math papers use "we" instead of "I"?

Awarded Nov 28, 2022 at 19:34

Zev Chonoles

127k21 gold badges311 silver badges523 bronze badges

If $A^2 = I$ (Identity Matrix) then $A = \pm I$

Awarded Nov 28, 2022 at 15:41

Martin Wanvik

2,89219 silver badges16 bronze badges

Showing the inequality $|\alpha + \beta|^p \leq 2^{p-1}(|\alpha|^p + |\beta|^p)$

Awarded Nov 26, 2022 at 4:11

Davide Giraudo

165k67 gold badges240 silver badges375 bronze badges

Fundamental Theorem of Calculus

Awarded Nov 21, 2022 at 16:28

Arturo Magidin

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