User leftaroundabout

40 votes

3 answers

10k views

Is it true that a space-filling curve cannot be injective everywhere?

asked Jun 3, 2011 at 22:28

80 votes

7 answers

10k views

Is linear algebra more “fully understood” than other maths disciplines?

asked Mar 16, 2016 at 21:03

0 votes

2 answers

3k views

How does the left singular value decomposition change when one duplicates a column in the original matrix?

asked Nov 25, 2012 at 17:53

8 votes

3 answers

2k views

Is self-adjointness really a property of an operator, or of an operator and an inner product?

asked Jan 23, 2017 at 22:33

7 votes

3 answers

1k views

How is the uniform boundedness principle compatible with this seemingly weak convergent sequence?

asked May 19, 2011 at 10:36

2 votes

2 answers

1k views

Why is the hyperbolic plane homeomorphic to $\mathbb{R}^2$, whilst the 2-sphere isn't?

asked Mar 30, 2018 at 15:19

12 votes

2 answers

457 views

Is it mathematically problematic to consider the complex space of real(!)-valued functions?

asked Apr 20, 2017 at 21:00

9 votes

1 answer

370 views

What is the name for the archetypical example of a test function, $\varphi(x)=e^{1/(x^2-1)}$?

asked May 23, 2011 at 20:57

9 votes

2 answers

296 views

How should one interpret an interval like $[2,1]$?

asked Aug 14, 2011 at 21:29

3 votes

1 answer

194 views

Why not define the Conway base-5 function, instead of base-13?

asked Feb 15, 2014 at 10:59

8 votes

1 answer

153 views

Is there a permutation on $\mathbb{N}$ that, if repeated often enough, eventually shuffles the whole set?

asked Aug 19, 2016 at 12:18

1 vote

1 answer

147 views

Can you say that almost all $\mathcal{C}^\infty$ functions are not polynomials?

asked Mar 29, 2015 at 12:50

2 votes

1 answer

115 views

Are functions between sets of global elements of objects isomorphic to the hom-set between these objects?

asked Feb 6, 2014 at 13:29

2 votes

1 answer

102 views

What do you call a directed graph in which reachablility is a symmetric relation?

asked Jun 26, 2016 at 20:15

2 votes

3 answers

90 views

Is there any shorter term for manifolds with boundary?

asked Sep 10, 2015 at 12:40

6 votes

0 answers

84 views

Is there a way to define the concept of manifolds so it looks more like “generalised affine spaces”?

asked Jan 26, 2015 at 12:08

2 votes

1 answer

83 views

Would it be appropriate to use "power" to describe an $n$-fold fold of a number with some associative binary operation? Is there a better expression?

asked Nov 3, 2011 at 18:45

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17 Questions

Is it true that a space-filling curve cannot be injective everywhere?

Is linear algebra more “fully understood” than other maths disciplines?

How does the left singular value decomposition change when one duplicates a column in the original matrix?

Is self-adjointness really a property of an operator, or of an operator and an inner product?

How is the uniform boundedness principle compatible with this seemingly weak convergent sequence?

Why is the hyperbolic plane homeomorphic to $\mathbb{R}^2$, whilst the 2-sphere isn't?

Is it mathematically problematic to consider the complex space of real(!)-valued functions?

What is the name for the archetypical example of a test function, $\varphi(x)=e^{1/(x^2-1)}$?

How should one interpret an interval like $[2,1]$?

Why not define the Conway base-5 function, instead of base-13?

Is there a permutation on $\mathbb{N}$ that, if repeated often enough, eventually shuffles the whole set?

Can you say that almost all $\mathcal{C}^\infty$ functions are not polynomials?

Are functions between sets of global elements of objects isomorphic to the hom-set between these objects?

What do you call a directed graph in which reachablility is a symmetric relation?

Is there any shorter term for manifolds with boundary?

Is there a way to define the concept of manifolds so it looks more like “generalised affine spaces”?

Would it be appropriate to use "power" to describe an $n$-fold fold of a number with some associative binary operation? Is there a better expression?