User Matematleta

30 votes

Monoid as a single object category

answered Jun 20, 2015 at 15:34

28 votes

Can every manifold be turned into a Lie group?

answered Dec 18, 2019 at 23:31

22 votes

Proof of the second symmetric derivative

answered Jun 2, 2016 at 0:21

15 votes

Convergence of $\sum_{n=1}^{\infty}e^{-\sqrt{n}}$ using the integral test

answered Oct 8, 2018 at 22:20

15 votes

Proof verification that bijective local diffeomorphisms are diffeomorphisms

answered Jul 20, 2019 at 13:20

14 votes

Idea behind "reparameterization hiding a corner" in single variable calculus

answered Aug 16, 2020 at 0:19

14 votes

Prove that an increasing and surjective function is continuous.

answered May 28, 2015 at 19:24

13 votes

Accepted

Proof about Borel sigma-algebra on $ \mathbb{R}^2$

answered Dec 23, 2016 at 16:13

11 votes

Uniqueness of adjoint functors up to isomorphism

answered Mar 5, 2015 at 23:13

10 votes

Show that the Stone–Čech compactification $\beta \mathbb{Z}$ is not metrizable.

answered Aug 15, 2016 at 3:58

10 votes

Accepted

Equivalent definition of a quotient map

answered Sep 17, 2018 at 1:50

9 votes

Accepted

Showing $f(x) = \frac{1}{\sqrt x}$ is Lebesgue integrable on $(0,1]$

answered Dec 12, 2018 at 20:04

8 votes

If $f(x)=8x^3+3x$ , $x\in\mathbb{R}$, how do I find $\lim_{x \to \infty}\frac {f^{-1}(8x)-f^{-1}(x)}{x^{1/3}}$?

answered Jun 16, 2015 at 4:12

8 votes

How to show $R_l$ is Lindelöf space?

answered Apr 11, 2019 at 17:01

7 votes

Accepted

Lee - Introduction to Smooth Manifolds Problem 8-9

answered Dec 28, 2019 at 17:27

7 votes

Prove that there exists a linear transformation $T: R^n \rightarrow R^n$ such that $T^3 = T$, and T has at least three distinct eigenvalues.

answered Jun 22, 2015 at 13:09

7 votes

Prob. 4, Sec. 28, in Munkres' TOPOLOGY, 2nd ed: For $T_1$-spaces countable compactness is equivalent to limit-point-compactness.

answered Jul 13, 2015 at 23:46

7 votes

Accepted

If function is measurable on an interval, is it measurable on its subinterval?

answered Jun 17, 2016 at 20:39

7 votes

Accepted

Question about Vitali Covering

answered Nov 12, 2018 at 3:07

6 votes

Accepted

Proving the continuity of the Cantor Function

answered Dec 2, 2018 at 2:28

6 votes

Proving $|z-1|<|z-i|$ is an open set

answered Aug 31, 2016 at 17:55

6 votes

Confused about the Arrow Category

answered Jul 19, 2015 at 18:59

6 votes

10th derivative of a function

answered Aug 4, 2015 at 15:59

6 votes

Accepted

Finding the volume of a solid bounded by a sphere and a paraboloid

answered Jul 30, 2015 at 20:19

6 votes

Proposed proof of: If $A \subset B \subset \bar{A}$ and $A$ is connected, then $B$ is connected

answered Jun 17, 2015 at 16:23

6 votes

High school contest math problem

answered Dec 31, 2019 at 14:56

6 votes

Accepted

Why $\{ \lambda x + (1-\lambda){y}\;\lvert\; \lambda \in [0,1] \}$ represents the line segment between $x,y$?

answered Nov 16, 2019 at 23:31

6 votes

Accepted

Show that convolution of two $L^1(\mathbb{R})$ functions is continuous

answered Feb 22, 2019 at 0:40

6 votes

Accepted

The set at which a function's oscillation is at least $\epsilon$ is closed

answered Feb 23, 2019 at 17:34

6 votes

Terence Tao, Analysis I, Ex. 5.4.5: There is a rational between any two reals

answered Nov 13, 2019 at 22:04

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1,314 Answers

Monoid as a single object category

Can every manifold be turned into a Lie group?

Proof of the second symmetric derivative

Convergence of $\sum_{n=1}^{\infty}e^{-\sqrt{n}}$ using the integral test

Proof verification that bijective local diffeomorphisms are diffeomorphisms

Idea behind "reparameterization hiding a corner" in single variable calculus

Prove that an increasing and surjective function is continuous.

Proof about Borel sigma-algebra on $ \mathbb{R}^2$

Uniqueness of adjoint functors up to isomorphism

Show that the Stone–Čech compactification $\beta \mathbb{Z}$ is not metrizable.

Equivalent definition of a quotient map

Showing $f(x) = \frac{1}{\sqrt x}$ is Lebesgue integrable on $(0,1]$

If $f(x)=8x^3+3x$ , $x\in\mathbb{R}$, how do I find $\lim_{x \to \infty}\frac {f^{-1}(8x)-f^{-1}(x)}{x^{1/3}}$?

How to show $R_l$ is Lindelöf space?

Lee - Introduction to Smooth Manifolds Problem 8-9

Prove that there exists a linear transformation $T: R^n \rightarrow R^n$ such that $T^3 = T$, and T has at least three distinct eigenvalues.

Prob. 4, Sec. 28, in Munkres' TOPOLOGY, 2nd ed: For $T_1$-spaces countable compactness is equivalent to limit-point-compactness.

If function is measurable on an interval, is it measurable on its subinterval?

Question about Vitali Covering

Proving the continuity of the Cantor Function

Proving $|z-1|<|z-i|$ is an open set

Confused about the Arrow Category

10th derivative of a function

Finding the volume of a solid bounded by a sphere and a paraboloid

Proposed proof of: If $A \subset B \subset \bar{A}$ and $A$ is connected, then $B$ is connected

High school contest math problem

Why $\{ \lambda x + (1-\lambda){y}\;\lvert\; \lambda \in [0,1] \}$ represents the line segment between $x,y$?

Show that convolution of two $L^1(\mathbb{R})$ functions is continuous

The set at which a function's oscillation is at least $\epsilon$ is closed

Terence Tao, Analysis I, Ex. 5.4.5: There is a rational between any two reals