User Rasmus

73 votes

Accepted

Does $G\cong G/H$ imply that $H$ is trivial?

answered Nov 7, 2011 at 13:46

49 votes

Accepted

Prove that $\lfloor0.999\dots\rfloor= ?$ $0$ or $1$?

limits decimal-expansion

answered Oct 16, 2013 at 13:13

42 votes

When to learn category theory?

abstract-algebra category-theory education learning

answered Feb 9, 2011 at 8:17

34 votes

Accepted

Is a Fourier transform a change of basis, or is it a linear transformation?

linear-algebra fourier-analysis transformation

answered Mar 23, 2012 at 9:31

27 votes

Tensor product and Kronecker Product

tensor-products tensors

answered Sep 28, 2012 at 12:22

26 votes

Accepted

Function theory: codomain and image, difference between them

functions terminology

answered Jan 8, 2012 at 14:53

21 votes

Accepted

Is it possible to 'split' coin flipping 3 ways?

probability fair-division

answered Aug 13, 2010 at 15:21

19 votes

Are any two open connected subsets of $\Bbb{R}^n$ homeomorphic?

general-topology

answered Feb 25, 2013 at 17:57

15 votes

Vivid examples of vector spaces?

soft-question education

answered Sep 22, 2010 at 17:43

14 votes

Can spectrum "specify" an operator?

soft-question functional-analysis spectral-theory

answered Apr 26, 2011 at 22:16

13 votes

Accepted

Is $O$ in $f \in O(g)$ a total partial order on the set of functions?

real-analysis

answered Mar 6, 2011 at 19:12

13 votes

Accepted

Flat not projective, projective not free

commutative-algebra modules

answered Mar 24, 2011 at 11:42

13 votes

Accepted

What are the sub-sets of a null set?

elementary-set-theory

answered Jun 13, 2011 at 14:06

13 votes

Accepted

Connections between K-Theory and PDEs?

general-topology algebraic-geometry algebraic-topology partial-differential-equations

answered Sep 29, 2010 at 16:35

13 votes

Accepted

Weierstrass M-Test

math-history

answered Feb 19, 2011 at 13:34

12 votes

Evaluating the integral $\int_0^\infty \frac{\sin x} x \,\mathrm dx = \frac \pi 2$?

calculus complex-analysis analysis definite-integrals improper-integrals

answered Sep 22, 2010 at 19:19

11 votes

Accepted

Pseudoinverse matrix and SVD

linear-algebra matrices pseudoinverse

answered Feb 1, 2011 at 22:31

11 votes

False beliefs in mathematics (conceptual errors made despite, or because of, mathematical education)

big-list education learning

answered Oct 26, 2010 at 13:55

10 votes

Accepted

How can I prove $\underbrace{\int \ldots \int}_{n} |x| dx = \frac{x^n |x|}{n+1}+C$?

calculus

answered Oct 9, 2010 at 19:33

10 votes

Accepted

sigma algebra generated by random variable

probability-theory measure-theory

answered Oct 24, 2010 at 21:41

10 votes

Why is the 3D case so rich?

big-list low-dimensional-topology

answered Aug 23, 2010 at 8:32

10 votes

Accepted

Adding powers of $i$

sequences-and-series complex-numbers

answered Sep 5, 2010 at 13:31

10 votes

Probability of either dice showing a specific number

probability combinatorics dice

answered Jan 9, 2012 at 13:31

10 votes

Accepted

For integers $a$ and $b$, $ab=\text{lcm}(a,b)\cdot\text{hcf}(a,b)$

elementary-number-theory divisibility gcd-and-lcm least-common-multiple

answered Jun 11, 2011 at 21:18

10 votes

How to prove if function is increasing

combinatorics induction

answered Sep 15, 2012 at 10:02

9 votes

Accepted

Strong convergence does not imply operator norm convergence

functional-analysis

answered Aug 14, 2012 at 18:05

9 votes

Accepted

Function $f(x)$ similar to exp(x) where $-f(x)$ is approximately $f(-x)$

exponential-function

answered Jul 28, 2012 at 15:19

9 votes

Is Minkowski space not a metric space?

metric-spaces

answered Oct 14, 2013 at 18:55

9 votes

Accepted

Operator whose spectrum is given compact set

functional-analysis

answered Mar 23, 2011 at 16:33

9 votes

Accepted

Is there some universal sense of -ification (eg, groupification) in category theory

category-theory

answered Aug 16, 2010 at 18:46

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266 Answers

Does $G\cong G/H$ imply that $H$ is trivial?

Prove that $\lfloor0.999\dots\rfloor= ?$ $0$ or $1$?

When to learn category theory?

Is a Fourier transform a change of basis, or is it a linear transformation?

Tensor product and Kronecker Product

Function theory: codomain and image, difference between them

Is it possible to 'split' coin flipping 3 ways?

Are any two open connected subsets of $\Bbb{R}^n$ homeomorphic?

Vivid examples of vector spaces?

Can spectrum "specify" an operator?

Is $O$ in $f \in O(g)$ a total partial order on the set of functions?

Flat not projective, projective not free

What are the sub-sets of a null set?

Connections between K-Theory and PDEs?

Weierstrass M-Test

Evaluating the integral $\int_0^\infty \frac{\sin x} x \,\mathrm dx = \frac \pi 2$?

Pseudoinverse matrix and SVD

False beliefs in mathematics (conceptual errors made despite, or because of, mathematical education)

How can I prove $\underbrace{\int \ldots \int}_{n} |x| dx = \frac{x^n |x|}{n+1}+C$?

sigma algebra generated by random variable

Why is the 3D case so rich?

Adding powers of $i$

Probability of either dice showing a specific number

For integers $a$ and $b$, $ab=\text{lcm}(a,b)\cdot\text{hcf}(a,b)$

How to prove if function is increasing

Strong convergence does not imply operator norm convergence

Function $f(x)$ similar to exp(x) where $-f(x)$ is approximately $f(-x)$

Is Minkowski space not a metric space?

Operator whose spectrum is given compact set

Is there some universal sense of -ification (eg, groupification) in category theory