User Zzz

20 votes

1 answer

5k views

Proof that product topology of subspace is same as induced product topology

general-topology proof-verification

asked Nov 27, 2015 at 10:36

7 votes

2 answers

4k views

Continuity of cartesian product of functions between topological spaces

asked Feb 26, 2016 at 11:54

6 votes

1 answer

1k views

Product space that is compact, but isn't sequentially compact

general-topology

asked Dec 3, 2015 at 17:52

4 votes

3 answers

224 views

Last digit of $1238237^{18238456}$

elementary-number-theory

asked Jul 30, 2015 at 18:14

2 votes

1 answer

2k views

If $\gcd(a,b)=1$, then there exists integers $x$ and $y$ such that $xa + yb = 1$

abstract-algebra

asked Jul 29, 2015 at 0:43

2 votes

3 answers

571 views

If $X$ is compact metric space, then $X$ is bounded

general-topology

asked Oct 30, 2015 at 22:06

2 votes

1 answer

60 views

Prove that norm $\| y \|=\sqrt{\int_{a}^{b}| y(x)|^2 dx}$ forms a linear space

functional-analysis proof-verification

asked Jul 20, 2016 at 18:45

2 votes

0 answers

122 views

Definition of extrema in calculus of variations

functional-analysis definition

asked Jun 26, 2016 at 12:06

1 vote

0 answers

66 views

Taylor's theorem for function F(x,y,z)

multivariable-calculus taylor-expansion definition

asked Oct 3, 2016 at 17:04

1 vote

2 answers

89 views

Formalize equivalence classes [closed]

logic first-order-logic

asked May 8, 2017 at 7:31

1 vote

2 answers

125 views

Incomplete subspace of Banach space

functional-analysis proof-writing

asked Aug 26, 2016 at 14:23

1 vote

1 answer

418 views

Calculus of variations and Bernstein's theorem

functional-analysis proof-explanation

asked Sep 1, 2016 at 10:51

1 vote

1 answer

115 views

Euler-Lagrange example proof

functional-analysis proof-verification euler-lagrange-equation

asked Sep 4, 2016 at 14:39

1 vote

1 answer

319 views

Definition of a neighborhood in normed linear space?

functional-analysis definition

asked Sep 26, 2016 at 18:33

1 vote

1 answer

172 views

If $E\subseteq X$ is connected, $E\cap A\neq\emptyset$ and $E\cap(X\setminus A)\neq\emptyset$ then $E\cap\partial A\neq\emptyset$

general-topology proof-verification

asked Mar 10, 2016 at 9:05

1 vote

4 answers

241 views

Every half-plane $H=\{(x,y)\in\mathbb{R}^{2}\mid ax+by+c\geq 0\}$ is connected

general-topology

asked Mar 10, 2016 at 20:23

1 vote

1 answer

116 views

Homeomorphism between $X/\tilde~$ and $Y/\tilde~'$

general-topology

asked Mar 15, 2016 at 17:45

1 vote

2 answers

271 views

Continuous surjection from simple closed curve to unit circle

general-topology

asked Nov 21, 2015 at 20:27

1 vote

1 answer

123 views

Define product topology for subspace

general-topology

asked Nov 26, 2015 at 22:41

0 votes

2 answers

2k views

What are open subsets of half-open interval of $\mathbb{R}$?

general-topology

asked Oct 30, 2015 at 13:30

0 votes

0 answers

101 views

Sequence convergence in box topology

general-topology

asked Nov 24, 2015 at 20:32

0 votes

2 answers

57 views

Equivalance classes example

elementary-set-theory

asked Jan 7, 2016 at 19:59

0 votes

1 answer

3k views

Is epsilon a useless symbol and when epsilon does belong into CFL?

formal-languages

asked Feb 1, 2016 at 22:58

0 votes

1 answer

53 views

How to define that in which hierarchy certain language belongs?

formal-languages

asked Feb 2, 2016 at 18:22

0 votes

1 answer

73 views

Proof that $\{\,\left]a,\infty\right [\mid a\in\mathbb{R}\,\}\cup\{\mathbb{R} \}\cup\{\emptyset \}$ is topology of $\mathbb{R}$

general-topology proof-verification

asked Feb 6, 2016 at 18:45

0 votes

1 answer

43 views

$G=U\cap F$, where $U\subseteq X$ is closed, iff $G\subseteq F$ closed in $X$

general-topology

asked Feb 23, 2016 at 18:18

0 votes

1 answer

78 views

Validity at state w

asked Nov 7, 2015 at 20:41

0 votes

1 answer

374 views

$f$ is homeomorphism iff $A\subseteq X$ open iff $f(A)\subseteq Y$ is open

general-topology

asked Nov 13, 2015 at 10:21

0 votes

1 answer

88 views

Open map from $\mathbb{R}$ to Sierpinski space

general-topology

asked Nov 14, 2015 at 12:03

0 votes

2 answers

640 views

Open or closed mapping between closed disk and unit sphere

general-topology multivariable-calculus

asked Nov 16, 2015 at 21:28

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39 Questions

Proof that product topology of subspace is same as induced product topology

Continuity of cartesian product of functions between topological spaces

Product space that is compact, but isn't sequentially compact

Last digit of $1238237^{18238456}$

If $\gcd(a,b)=1$, then there exists integers $x$ and $y$ such that $xa + yb = 1$

If $X$ is compact metric space, then $X$ is bounded

Prove that norm $\| y \|=\sqrt{\int_{a}^{b}| y(x)|^2 dx}$ forms a linear space

Definition of extrema in calculus of variations

Taylor's theorem for function F(x,y,z)

Formalize equivalence classes [closed]

Incomplete subspace of Banach space

Calculus of variations and Bernstein's theorem

Euler-Lagrange example proof

Definition of a neighborhood in normed linear space?

If $E\subseteq X$ is connected, $E\cap A\neq\emptyset$ and $E\cap(X\setminus A)\neq\emptyset$ then $E\cap\partial A\neq\emptyset$

Every half-plane $H=\{(x,y)\in\mathbb{R}^{2}\mid ax+by+c\geq 0\}$ is connected

Homeomorphism between $X/\tilde~$ and $Y/\tilde~'$

Continuous surjection from simple closed curve to unit circle

Define product topology for subspace

What are open subsets of half-open interval of $\mathbb{R}$?

Sequence convergence in box topology

Equivalance classes example

Is epsilon a useless symbol and when epsilon does belong into CFL?

How to define that in which hierarchy certain language belongs?

Proof that $\{\,\left]a,\infty\right [\mid a\in\mathbb{R}\,\}\cup\{\mathbb{R} \}\cup\{\emptyset \}$ is topology of $\mathbb{R}$

$G=U\cap F$, where $U\subseteq X$ is closed, iff $G\subseteq F$ closed in $X$

Validity at state w

$f$ is homeomorphism iff $A\subseteq X$ open iff $f(A)\subseteq Y$ is open

Open map from $\mathbb{R}$ to Sierpinski space

Open or closed mapping between closed disk and unit sphere