Difficultly understanding the inclusion exclusion identity because of difficult notation
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This is the property: $mathbb{P}(E1cup E2cup ...cup En)= sum_{i}^{n} mathbb{P}(E1) - sum_{i1<i2} mathbb{P}(Ei1Ei2) + ... + -1^{r+1}sum_{i1<i2<...<ir} mathbb{P}(Ei1Ei2...Eir) + -1^{r+1}sum_{1<2<...<n} mathbb{P}(E1E2...En) $
While I understand the property, I don’t understand the summation symbol notation. What does the book mean by $sum_{i1<i2<...<ir}$? Can someone draw out specifically what this sum is so I can understand it? I lost my question privileges due to this question but can someone please let me know what about this question was so bad? I couldn't find the syntax anywhere.
calculus probability
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add a comment |
$begingroup$
This is the property: $mathbb{P}(E1cup E2cup ...cup En)= sum_{i}^{n} mathbb{P}(E1) - sum_{i1<i2} mathbb{P}(Ei1Ei2) + ... + -1^{r+1}sum_{i1<i2<...<ir} mathbb{P}(Ei1Ei2...Eir) + -1^{r+1}sum_{1<2<...<n} mathbb{P}(E1E2...En) $
While I understand the property, I don’t understand the summation symbol notation. What does the book mean by $sum_{i1<i2<...<ir}$? Can someone draw out specifically what this sum is so I can understand it? I lost my question privileges due to this question but can someone please let me know what about this question was so bad? I couldn't find the syntax anywhere.
calculus probability
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$begingroup$
I’m not sure why it isn’t showing the whole equation it shows up in my edit
$endgroup$
– Person
Dec 6 '18 at 3:48
$begingroup$
Learn how to write with latex .
$endgroup$
– tarit goswami
Dec 6 '18 at 4:03
$begingroup$
usecupfor $cup$ andsum_{i=1}^{n}for $sum_{i=1}^{n}$.
$endgroup$
– Nosrati
Dec 6 '18 at 4:17
add a comment |
$begingroup$
This is the property: $mathbb{P}(E1cup E2cup ...cup En)= sum_{i}^{n} mathbb{P}(E1) - sum_{i1<i2} mathbb{P}(Ei1Ei2) + ... + -1^{r+1}sum_{i1<i2<...<ir} mathbb{P}(Ei1Ei2...Eir) + -1^{r+1}sum_{1<2<...<n} mathbb{P}(E1E2...En) $
While I understand the property, I don’t understand the summation symbol notation. What does the book mean by $sum_{i1<i2<...<ir}$? Can someone draw out specifically what this sum is so I can understand it? I lost my question privileges due to this question but can someone please let me know what about this question was so bad? I couldn't find the syntax anywhere.
calculus probability
$endgroup$
This is the property: $mathbb{P}(E1cup E2cup ...cup En)= sum_{i}^{n} mathbb{P}(E1) - sum_{i1<i2} mathbb{P}(Ei1Ei2) + ... + -1^{r+1}sum_{i1<i2<...<ir} mathbb{P}(Ei1Ei2...Eir) + -1^{r+1}sum_{1<2<...<n} mathbb{P}(E1E2...En) $
While I understand the property, I don’t understand the summation symbol notation. What does the book mean by $sum_{i1<i2<...<ir}$? Can someone draw out specifically what this sum is so I can understand it? I lost my question privileges due to this question but can someone please let me know what about this question was so bad? I couldn't find the syntax anywhere.
calculus probability
calculus probability
edited Dec 6 '18 at 17:53
Person
asked Dec 6 '18 at 3:46
PersonPerson
177
177
$begingroup$
I’m not sure why it isn’t showing the whole equation it shows up in my edit
$endgroup$
– Person
Dec 6 '18 at 3:48
$begingroup$
Learn how to write with latex .
$endgroup$
– tarit goswami
Dec 6 '18 at 4:03
$begingroup$
usecupfor $cup$ andsum_{i=1}^{n}for $sum_{i=1}^{n}$.
$endgroup$
– Nosrati
Dec 6 '18 at 4:17
add a comment |
$begingroup$
I’m not sure why it isn’t showing the whole equation it shows up in my edit
$endgroup$
– Person
Dec 6 '18 at 3:48
$begingroup$
Learn how to write with latex .
$endgroup$
– tarit goswami
Dec 6 '18 at 4:03
$begingroup$
usecupfor $cup$ andsum_{i=1}^{n}for $sum_{i=1}^{n}$.
$endgroup$
– Nosrati
Dec 6 '18 at 4:17
$begingroup$
I’m not sure why it isn’t showing the whole equation it shows up in my edit
$endgroup$
– Person
Dec 6 '18 at 3:48
$begingroup$
I’m not sure why it isn’t showing the whole equation it shows up in my edit
$endgroup$
– Person
Dec 6 '18 at 3:48
$begingroup$
Learn how to write with latex .
$endgroup$
– tarit goswami
Dec 6 '18 at 4:03
$begingroup$
Learn how to write with latex .
$endgroup$
– tarit goswami
Dec 6 '18 at 4:03
$begingroup$
use
cup for $cup$ and sum_{i=1}^{n} for $sum_{i=1}^{n}$.$endgroup$
– Nosrati
Dec 6 '18 at 4:17
$begingroup$
use
cup for $cup$ and sum_{i=1}^{n} for $sum_{i=1}^{n}$.$endgroup$
– Nosrati
Dec 6 '18 at 4:17
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
Some people would write the sum $sum_{i_1<i_2<cdots<i_r}$ as
$sum_{1 leq i_1<i_2<cdots<i_r leq n}$
in order to emphasize that all the variables $i_1,i_2,ldots,i_r$ have to be between $1$ and $n$ inclusive.
The $r$th sum can be rewritten in more basic summation notation as
$$
sum_{1 leq i_1<i_2<cdots<i_r leq n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r})
= sum_{i_1 = 1}^{n - r + 1}, sum_{i_2 = i_1 + 1}^{n - r + 2},
sum_{i_3 = i_2 + 1}^{n - r + 3} cdots sum_{i_{r-1} = i_{r-2} + 1}^{n - 1},
sum_{i_r = i_{r-1} + 1}^{n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r}).
$$
Each side of the equation ends up with $binom nr$ individual terms in the sum, one for each possible sequence of $r$ increasing integers where none is less than $1$ or greater than $n.$
Each of those sequences picks out a different subset of $r$ of the events in the set ${E_1, E_2, ldots, E_n}.$
Personally, I find the notation on the left is a lot easier to understand.
$endgroup$
add a comment |
$begingroup$
There are $r$ distinct terms, where $i_1, ldots, i_r$ are chosen from ${1, ldots, n}$ and satisfies $i_1 < i_2 < ldots, i_r}$.
For example if $n=4$, $r=3$,
$$(-1)^{r+1} sum_{i_1 < i_2<i_3}P(E_{i_1}cap E_{i_2}cap E_{i_3})=(-1) left( P(E_1 cap E_2 cap E_3) + P(E_1 cap E_2 cap E_4)+P(E_1 cap E_3 cap E_4)+P(E_2 cap E_3 cap E_3)right)$$
Using this notation avoid listing the same thing multiple times, for example $P(E_1 cap E_2 cap E_3) = P(E_3 cap E_2 cap E_1)$ and we don't want to list it twice.
$endgroup$
add a comment |
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2 Answers
2
active
oldest
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2 Answers
2
active
oldest
votes
active
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oldest
votes
$begingroup$
Some people would write the sum $sum_{i_1<i_2<cdots<i_r}$ as
$sum_{1 leq i_1<i_2<cdots<i_r leq n}$
in order to emphasize that all the variables $i_1,i_2,ldots,i_r$ have to be between $1$ and $n$ inclusive.
The $r$th sum can be rewritten in more basic summation notation as
$$
sum_{1 leq i_1<i_2<cdots<i_r leq n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r})
= sum_{i_1 = 1}^{n - r + 1}, sum_{i_2 = i_1 + 1}^{n - r + 2},
sum_{i_3 = i_2 + 1}^{n - r + 3} cdots sum_{i_{r-1} = i_{r-2} + 1}^{n - 1},
sum_{i_r = i_{r-1} + 1}^{n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r}).
$$
Each side of the equation ends up with $binom nr$ individual terms in the sum, one for each possible sequence of $r$ increasing integers where none is less than $1$ or greater than $n.$
Each of those sequences picks out a different subset of $r$ of the events in the set ${E_1, E_2, ldots, E_n}.$
Personally, I find the notation on the left is a lot easier to understand.
$endgroup$
add a comment |
$begingroup$
Some people would write the sum $sum_{i_1<i_2<cdots<i_r}$ as
$sum_{1 leq i_1<i_2<cdots<i_r leq n}$
in order to emphasize that all the variables $i_1,i_2,ldots,i_r$ have to be between $1$ and $n$ inclusive.
The $r$th sum can be rewritten in more basic summation notation as
$$
sum_{1 leq i_1<i_2<cdots<i_r leq n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r})
= sum_{i_1 = 1}^{n - r + 1}, sum_{i_2 = i_1 + 1}^{n - r + 2},
sum_{i_3 = i_2 + 1}^{n - r + 3} cdots sum_{i_{r-1} = i_{r-2} + 1}^{n - 1},
sum_{i_r = i_{r-1} + 1}^{n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r}).
$$
Each side of the equation ends up with $binom nr$ individual terms in the sum, one for each possible sequence of $r$ increasing integers where none is less than $1$ or greater than $n.$
Each of those sequences picks out a different subset of $r$ of the events in the set ${E_1, E_2, ldots, E_n}.$
Personally, I find the notation on the left is a lot easier to understand.
$endgroup$
add a comment |
$begingroup$
Some people would write the sum $sum_{i_1<i_2<cdots<i_r}$ as
$sum_{1 leq i_1<i_2<cdots<i_r leq n}$
in order to emphasize that all the variables $i_1,i_2,ldots,i_r$ have to be between $1$ and $n$ inclusive.
The $r$th sum can be rewritten in more basic summation notation as
$$
sum_{1 leq i_1<i_2<cdots<i_r leq n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r})
= sum_{i_1 = 1}^{n - r + 1}, sum_{i_2 = i_1 + 1}^{n - r + 2},
sum_{i_3 = i_2 + 1}^{n - r + 3} cdots sum_{i_{r-1} = i_{r-2} + 1}^{n - 1},
sum_{i_r = i_{r-1} + 1}^{n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r}).
$$
Each side of the equation ends up with $binom nr$ individual terms in the sum, one for each possible sequence of $r$ increasing integers where none is less than $1$ or greater than $n.$
Each of those sequences picks out a different subset of $r$ of the events in the set ${E_1, E_2, ldots, E_n}.$
Personally, I find the notation on the left is a lot easier to understand.
$endgroup$
Some people would write the sum $sum_{i_1<i_2<cdots<i_r}$ as
$sum_{1 leq i_1<i_2<cdots<i_r leq n}$
in order to emphasize that all the variables $i_1,i_2,ldots,i_r$ have to be between $1$ and $n$ inclusive.
The $r$th sum can be rewritten in more basic summation notation as
$$
sum_{1 leq i_1<i_2<cdots<i_r leq n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r})
= sum_{i_1 = 1}^{n - r + 1}, sum_{i_2 = i_1 + 1}^{n - r + 2},
sum_{i_3 = i_2 + 1}^{n - r + 3} cdots sum_{i_{r-1} = i_{r-2} + 1}^{n - 1},
sum_{i_r = i_{r-1} + 1}^{n} mathbb{P}(E_{i_1}E_{i_2}cdots E_{i_r}).
$$
Each side of the equation ends up with $binom nr$ individual terms in the sum, one for each possible sequence of $r$ increasing integers where none is less than $1$ or greater than $n.$
Each of those sequences picks out a different subset of $r$ of the events in the set ${E_1, E_2, ldots, E_n}.$
Personally, I find the notation on the left is a lot easier to understand.
answered Dec 6 '18 at 6:04
David KDavid K
53.7k342116
53.7k342116
add a comment |
add a comment |
$begingroup$
There are $r$ distinct terms, where $i_1, ldots, i_r$ are chosen from ${1, ldots, n}$ and satisfies $i_1 < i_2 < ldots, i_r}$.
For example if $n=4$, $r=3$,
$$(-1)^{r+1} sum_{i_1 < i_2<i_3}P(E_{i_1}cap E_{i_2}cap E_{i_3})=(-1) left( P(E_1 cap E_2 cap E_3) + P(E_1 cap E_2 cap E_4)+P(E_1 cap E_3 cap E_4)+P(E_2 cap E_3 cap E_3)right)$$
Using this notation avoid listing the same thing multiple times, for example $P(E_1 cap E_2 cap E_3) = P(E_3 cap E_2 cap E_1)$ and we don't want to list it twice.
$endgroup$
add a comment |
$begingroup$
There are $r$ distinct terms, where $i_1, ldots, i_r$ are chosen from ${1, ldots, n}$ and satisfies $i_1 < i_2 < ldots, i_r}$.
For example if $n=4$, $r=3$,
$$(-1)^{r+1} sum_{i_1 < i_2<i_3}P(E_{i_1}cap E_{i_2}cap E_{i_3})=(-1) left( P(E_1 cap E_2 cap E_3) + P(E_1 cap E_2 cap E_4)+P(E_1 cap E_3 cap E_4)+P(E_2 cap E_3 cap E_3)right)$$
Using this notation avoid listing the same thing multiple times, for example $P(E_1 cap E_2 cap E_3) = P(E_3 cap E_2 cap E_1)$ and we don't want to list it twice.
$endgroup$
add a comment |
$begingroup$
There are $r$ distinct terms, where $i_1, ldots, i_r$ are chosen from ${1, ldots, n}$ and satisfies $i_1 < i_2 < ldots, i_r}$.
For example if $n=4$, $r=3$,
$$(-1)^{r+1} sum_{i_1 < i_2<i_3}P(E_{i_1}cap E_{i_2}cap E_{i_3})=(-1) left( P(E_1 cap E_2 cap E_3) + P(E_1 cap E_2 cap E_4)+P(E_1 cap E_3 cap E_4)+P(E_2 cap E_3 cap E_3)right)$$
Using this notation avoid listing the same thing multiple times, for example $P(E_1 cap E_2 cap E_3) = P(E_3 cap E_2 cap E_1)$ and we don't want to list it twice.
$endgroup$
There are $r$ distinct terms, where $i_1, ldots, i_r$ are chosen from ${1, ldots, n}$ and satisfies $i_1 < i_2 < ldots, i_r}$.
For example if $n=4$, $r=3$,
$$(-1)^{r+1} sum_{i_1 < i_2<i_3}P(E_{i_1}cap E_{i_2}cap E_{i_3})=(-1) left( P(E_1 cap E_2 cap E_3) + P(E_1 cap E_2 cap E_4)+P(E_1 cap E_3 cap E_4)+P(E_2 cap E_3 cap E_3)right)$$
Using this notation avoid listing the same thing multiple times, for example $P(E_1 cap E_2 cap E_3) = P(E_3 cap E_2 cap E_1)$ and we don't want to list it twice.
answered Dec 6 '18 at 5:45
Siong Thye GohSiong Thye Goh
100k1466117
100k1466117
add a comment |
add a comment |
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$begingroup$
I’m not sure why it isn’t showing the whole equation it shows up in my edit
$endgroup$
– Person
Dec 6 '18 at 3:48
$begingroup$
Learn how to write with latex .
$endgroup$
– tarit goswami
Dec 6 '18 at 4:03
$begingroup$
use
cupfor $cup$ andsum_{i=1}^{n}for $sum_{i=1}^{n}$.$endgroup$
– Nosrati
Dec 6 '18 at 4:17