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What is a function that separates points of a manifold? [on hold]
degree of differentiability of a manifold at a point$C(X)$ separates points?Why continuous paths implies smooth path on the manifold?What does it mean to “calculate in local coordinates” on a manifold?Closed ball not a manifold.What is the difference between intrinsic and extrinsic manifold?Showing an algebra separates pointsShow that the graph of $f$ is an immersed manifoldDerivation of a function on a manifoldHow can we show that $C_c^infty(mathbb R)$ strongly separates points?
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In the context of differential geometry, what is a function that separates points of a manifold?
general-topology differential-geometry
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put on hold as off-topic by Saad, dantopa, Parcly Taxel, Lord Shark the Unknown, Cesareo 12 hours ago
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Saad, dantopa, Parcly Taxel
add a comment |
$begingroup$
In the context of differential geometry, what is a function that separates points of a manifold?
general-topology differential-geometry
$endgroup$
put on hold as off-topic by Saad, dantopa, Parcly Taxel, Lord Shark the Unknown, Cesareo 12 hours ago
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Saad, dantopa, Parcly Taxel
$begingroup$
Can you give an example of what you mean with two points on a plane in $mathbb R^3 ? $
$endgroup$
– Narasimham
14 hours ago
add a comment |
$begingroup$
In the context of differential geometry, what is a function that separates points of a manifold?
general-topology differential-geometry
$endgroup$
In the context of differential geometry, what is a function that separates points of a manifold?
general-topology differential-geometry
general-topology differential-geometry
edited yesterday
YuiTo Cheng
2,0532637
2,0532637
asked yesterday
mattiav27mattiav27
599
599
put on hold as off-topic by Saad, dantopa, Parcly Taxel, Lord Shark the Unknown, Cesareo 12 hours ago
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Saad, dantopa, Parcly Taxel
put on hold as off-topic by Saad, dantopa, Parcly Taxel, Lord Shark the Unknown, Cesareo 12 hours ago
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Saad, dantopa, Parcly Taxel
$begingroup$
Can you give an example of what you mean with two points on a plane in $mathbb R^3 ? $
$endgroup$
– Narasimham
14 hours ago
add a comment |
$begingroup$
Can you give an example of what you mean with two points on a plane in $mathbb R^3 ? $
$endgroup$
– Narasimham
14 hours ago
$begingroup$
Can you give an example of what you mean with two points on a plane in $mathbb R^3 ? $
$endgroup$
– Narasimham
14 hours ago
$begingroup$
Can you give an example of what you mean with two points on a plane in $mathbb R^3 ? $
$endgroup$
– Narasimham
14 hours ago
add a comment |
3 Answers
3
active
oldest
votes
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If you have a family $mathcal F$ of functions from a set $X$ into some other set, we say that it separates the points of $x$ if, for each $x_1,x_2in X$ with $x_1neq x_2$, there is some $finmathcal F$ such that $f(x_1)neq f(x_2)$.
So, if $mathcal F$ consists of a single function $f$, this is the same thing as asserting that $f$ is injective.
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$begingroup$
@ Jose: you should ad: $x_1 ne x_2.$
$endgroup$
– Fred
yesterday
$begingroup$
@Fred I've edited my answer. Thank you.
$endgroup$
– José Carlos Santos
yesterday
add a comment |
$begingroup$
A function that separates points is a (smooth) real-valued function which has different value at the different points. If we only have two points, it is possible (depending on your lecturer and / or textbook author) that such a function is required to have the value $0$ at one point and $1$ at the other.
$endgroup$
add a comment |
$begingroup$
Let $A$ and $B$ be sets and let $S$ be a set of functions $f:A to B.$ $S$ is said to separate the points of $A$, if for any $x,y in A$ with $x ne y$, there is $f in S$ such that $f(x) ne f(y)$.
$endgroup$
add a comment |
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
If you have a family $mathcal F$ of functions from a set $X$ into some other set, we say that it separates the points of $x$ if, for each $x_1,x_2in X$ with $x_1neq x_2$, there is some $finmathcal F$ such that $f(x_1)neq f(x_2)$.
So, if $mathcal F$ consists of a single function $f$, this is the same thing as asserting that $f$ is injective.
$endgroup$
$begingroup$
@ Jose: you should ad: $x_1 ne x_2.$
$endgroup$
– Fred
yesterday
$begingroup$
@Fred I've edited my answer. Thank you.
$endgroup$
– José Carlos Santos
yesterday
add a comment |
$begingroup$
If you have a family $mathcal F$ of functions from a set $X$ into some other set, we say that it separates the points of $x$ if, for each $x_1,x_2in X$ with $x_1neq x_2$, there is some $finmathcal F$ such that $f(x_1)neq f(x_2)$.
So, if $mathcal F$ consists of a single function $f$, this is the same thing as asserting that $f$ is injective.
$endgroup$
$begingroup$
@ Jose: you should ad: $x_1 ne x_2.$
$endgroup$
– Fred
yesterday
$begingroup$
@Fred I've edited my answer. Thank you.
$endgroup$
– José Carlos Santos
yesterday
add a comment |
$begingroup$
If you have a family $mathcal F$ of functions from a set $X$ into some other set, we say that it separates the points of $x$ if, for each $x_1,x_2in X$ with $x_1neq x_2$, there is some $finmathcal F$ such that $f(x_1)neq f(x_2)$.
So, if $mathcal F$ consists of a single function $f$, this is the same thing as asserting that $f$ is injective.
$endgroup$
If you have a family $mathcal F$ of functions from a set $X$ into some other set, we say that it separates the points of $x$ if, for each $x_1,x_2in X$ with $x_1neq x_2$, there is some $finmathcal F$ such that $f(x_1)neq f(x_2)$.
So, if $mathcal F$ consists of a single function $f$, this is the same thing as asserting that $f$ is injective.
edited yesterday
answered yesterday
José Carlos SantosJosé Carlos Santos
168k22132236
168k22132236
$begingroup$
@ Jose: you should ad: $x_1 ne x_2.$
$endgroup$
– Fred
yesterday
$begingroup$
@Fred I've edited my answer. Thank you.
$endgroup$
– José Carlos Santos
yesterday
add a comment |
$begingroup$
@ Jose: you should ad: $x_1 ne x_2.$
$endgroup$
– Fred
yesterday
$begingroup$
@Fred I've edited my answer. Thank you.
$endgroup$
– José Carlos Santos
yesterday
$begingroup$
@ Jose: you should ad: $x_1 ne x_2.$
$endgroup$
– Fred
yesterday
$begingroup$
@ Jose: you should ad: $x_1 ne x_2.$
$endgroup$
– Fred
yesterday
$begingroup$
@Fred I've edited my answer. Thank you.
$endgroup$
– José Carlos Santos
yesterday
$begingroup$
@Fred I've edited my answer. Thank you.
$endgroup$
– José Carlos Santos
yesterday
add a comment |
$begingroup$
A function that separates points is a (smooth) real-valued function which has different value at the different points. If we only have two points, it is possible (depending on your lecturer and / or textbook author) that such a function is required to have the value $0$ at one point and $1$ at the other.
$endgroup$
add a comment |
$begingroup$
A function that separates points is a (smooth) real-valued function which has different value at the different points. If we only have two points, it is possible (depending on your lecturer and / or textbook author) that such a function is required to have the value $0$ at one point and $1$ at the other.
$endgroup$
add a comment |
$begingroup$
A function that separates points is a (smooth) real-valued function which has different value at the different points. If we only have two points, it is possible (depending on your lecturer and / or textbook author) that such a function is required to have the value $0$ at one point and $1$ at the other.
$endgroup$
A function that separates points is a (smooth) real-valued function which has different value at the different points. If we only have two points, it is possible (depending on your lecturer and / or textbook author) that such a function is required to have the value $0$ at one point and $1$ at the other.
answered yesterday
ArthurArthur
118k7118201
118k7118201
add a comment |
add a comment |
$begingroup$
Let $A$ and $B$ be sets and let $S$ be a set of functions $f:A to B.$ $S$ is said to separate the points of $A$, if for any $x,y in A$ with $x ne y$, there is $f in S$ such that $f(x) ne f(y)$.
$endgroup$
add a comment |
$begingroup$
Let $A$ and $B$ be sets and let $S$ be a set of functions $f:A to B.$ $S$ is said to separate the points of $A$, if for any $x,y in A$ with $x ne y$, there is $f in S$ such that $f(x) ne f(y)$.
$endgroup$
add a comment |
$begingroup$
Let $A$ and $B$ be sets and let $S$ be a set of functions $f:A to B.$ $S$ is said to separate the points of $A$, if for any $x,y in A$ with $x ne y$, there is $f in S$ such that $f(x) ne f(y)$.
$endgroup$
Let $A$ and $B$ be sets and let $S$ be a set of functions $f:A to B.$ $S$ is said to separate the points of $A$, if for any $x,y in A$ with $x ne y$, there is $f in S$ such that $f(x) ne f(y)$.
answered yesterday
FredFred
48.3k1849
48.3k1849
add a comment |
add a comment |
$begingroup$
Can you give an example of what you mean with two points on a plane in $mathbb R^3 ? $
$endgroup$
– Narasimham
14 hours ago