User SvanN - Mathematics Stack Exchange

6 votes

Accepted

Example of a linear transformation where kernel = image

answered Jul 30, 2017 at 14:46

5 votes

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If a subset of a partially ordered set has exactly one minimal element, must that element be a smallest element?

answered May 14, 2017 at 19:02

5 votes

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Does this function have countably or uncountably many discontinuities?

answered Jun 16, 2017 at 8:06

5 votes

Limit of $f(x)\cdot g(x)$ given that $\lim_{x\to 0}{\frac{f(x)}{\sin(2x)}}=2$ and $\lim_{x\to 0}{(\sqrt{x+4}-2)\cdot{g(x)}}=5$

answered Aug 11, 2017 at 9:48

5 votes

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Show that a function $f: A \to B$ is surjective if and only if it has a right inverse.

answered Dec 21, 2018 at 16:07

4 votes

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integral of a k-form over an oriented compact manifold

answered Jan 9, 2019 at 18:29

4 votes

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An Example of a Non-continuous Injection on a Real Interval, that is Not Strictly Monotonic.

answered Nov 17, 2018 at 13:11

4 votes

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Is this a valid proof to prove that if $a_n$ converges, then $a_{n+1}-a_{n}$ converges to $0$? by definition

answered May 27, 2017 at 10:25

4 votes

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Is it true for a bilinear function function that $\phi(x,y)=\phi (x+x+x+\dots,y)$? If so, how can we construct a bilinear function with this property?

answered Jun 3, 2017 at 12:24

4 votes

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Proof for triangle inequality generalized to integrals

answered Jul 29, 2017 at 13:48

3 votes

Need a formula for $\frac{d}{dx}f(g(x), h(x))$

answered Aug 4, 2017 at 17:08

3 votes

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Fixed Point of function $f([0,1] \supset[0,1] $

answered Aug 23, 2017 at 10:38

3 votes

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Compactness of a subset of $\mathbb{Q}$

answered Aug 23, 2017 at 11:23

3 votes

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Equivalent limit definition

answered Aug 11, 2017 at 9:54

2 votes

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Measure theory in practice

answered Aug 27, 2017 at 15:35

2 votes

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Show $f(x)=2x$ is measurable.

answered Jan 31, 2018 at 16:03

2 votes

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About every subgroup of $ ( \mathbb{Z} , + ) $ being cyclic.

answered Dec 21, 2018 at 18:23

2 votes

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Right inverse implies surjective function

answered Dec 24, 2018 at 16:23

2 votes

Accepted

(Prove or Disprove) If $X$ is a metric space, then the Borel $\sigma$-algebra ${\cal B}_X$ contains every countable subset of $X$.

answered Jan 21, 2019 at 7:02

2 votes

Accepted

Find the limit , Show that $\{F_n\}$ converges uniformly to $F$ on closed subsets of $S$, but not on $S$. $F_n(x) = x^n \sin nx, S=(-1,1)$

answered Aug 21, 2017 at 17:25

2 votes

Accepted

Understanding $f(x)=O(g(x))$ as $x \to c$ of two infinitely-small functions

answered Aug 13, 2017 at 17:12

2 votes

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$O(\eta_{n}^2)$ term in the expansion of $f(x^* + \eta_{n})$

answered Jul 29, 2017 at 14:29

2 votes

One stick and Pythagoras

answered Jul 13, 2017 at 16:45

2 votes

Graph that is not a tree, with Order>Size

answered May 14, 2017 at 18:19

2 votes

Accepted

Screen display ratios

answered Jul 10, 2017 at 16:47

2 votes

Accepted

Is $(Pf)(x)=(f(x)+f(−x))/2$ a linear map?

answered Jun 11, 2017 at 10:46

1 vote

Algebraic and Geometric Multiplicities For An Orthogonal Projection and Reflection

answered Jun 14, 2017 at 15:57

1 vote

How to prove convergence of $\int_0^{\infty}{\frac{\sin(x)}{x}dx}$ without evaluating it

answered Jun 14, 2017 at 17:28

1 vote

Accepted

Matrix exponential of any matrix

answered Jun 15, 2017 at 11:50

1 vote

Let $L$ a linear operator. Show that if $L$ is injective, then $\det(L)\neq 0$

answered Jul 10, 2017 at 16:50

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64 Answers

Example of a linear transformation where kernel = image

If a subset of a partially ordered set has exactly one minimal element, must that element be a smallest element?

Does this function have countably or uncountably many discontinuities?

Limit of $f(x)\cdot g(x)$ given that $\lim_{x\to 0}{\frac{f(x)}{\sin(2x)}}=2$ and $\lim_{x\to 0}{(\sqrt{x+4}-2)\cdot{g(x)}}=5$

Show that a function $f: A \to B$ is surjective if and only if it has a right inverse.

integral of a k-form over an oriented compact manifold

An Example of a Non-continuous Injection on a Real Interval, that is Not Strictly Monotonic.

Is this a valid proof to prove that if $a_n$ converges, then $a_{n+1}-a_{n}$ converges to $0$? by definition

Is it true for a bilinear function function that $\phi(x,y)=\phi (x+x+x+\dots,y)$? If so, how can we construct a bilinear function with this property?

Proof for triangle inequality generalized to integrals

Need a formula for $\frac{d}{dx}f(g(x), h(x))$

Fixed Point of function $f([0,1] \supset[0,1] $

Compactness of a subset of $\mathbb{Q}$

Equivalent limit definition

Measure theory in practice

Show $f(x)=2x$ is measurable.

About every subgroup of $ ( \mathbb{Z} , + ) $ being cyclic.

Right inverse implies surjective function

(Prove or Disprove) If $X$ is a metric space, then the Borel $\sigma$-algebra ${\cal B}_X$ contains every countable subset of $X$.

Find the limit , Show that $\{F_n\}$ converges uniformly to $F$ on closed subsets of $S$, but not on $S$. $F_n(x) = x^n \sin nx, S=(-1,1)$

Understanding $f(x)=O(g(x))$ as $x \to c$ of two infinitely-small functions

$O(\eta_{n}^2)$ term in the expansion of $f(x^* + \eta_{n})$

One stick and Pythagoras

Graph that is not a tree, with Order>Size

Screen display ratios

Is $(Pf)(x)=(f(x)+f(−x))/2$ a linear map?

Algebraic and Geometric Multiplicities For An Orthogonal Projection and Reflection

How to prove convergence of $\int_0^{\infty}{\frac{\sin(x)}{x}dx}$ without evaluating it

Matrix exponential of any matrix

Let $L$ a linear operator. Show that if $L$ is injective, then $\det(L)\neq 0$