Finite Field Subtraction {0, 1, x, y} [closed]












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In a finite field {$0, 1, x, y$} how does subtraction work? Let's say I want to do $y-y$ what does this equal?










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closed as off-topic by Saad, user10354138, Alexander Gruber Dec 4 '18 at 3:26


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 improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – Saad, user10354138, Alexander Gruber

If this question can be reworded to fit the rules in the help center, please edit the question.












  • 1




    $begingroup$
    If there is justice, then $y - y = 0$.
    $endgroup$
    – T. Bongers
    Dec 4 '18 at 0:27
















0












$begingroup$


In a finite field {$0, 1, x, y$} how does subtraction work? Let's say I want to do $y-y$ what does this equal?










share|cite|improve this question









$endgroup$



closed as off-topic by Saad, user10354138, Alexander Gruber Dec 4 '18 at 3:26


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 improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – Saad, user10354138, Alexander Gruber

If this question can be reworded to fit the rules in the help center, please edit the question.












  • 1




    $begingroup$
    If there is justice, then $y - y = 0$.
    $endgroup$
    – T. Bongers
    Dec 4 '18 at 0:27














0












0








0





$begingroup$


In a finite field {$0, 1, x, y$} how does subtraction work? Let's say I want to do $y-y$ what does this equal?










share|cite|improve this question









$endgroup$




In a finite field {$0, 1, x, y$} how does subtraction work? Let's say I want to do $y-y$ what does this equal?







finite-fields






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asked Dec 4 '18 at 0:23









Emma PascoeEmma Pascoe

161




161




closed as off-topic by Saad, user10354138, Alexander Gruber Dec 4 '18 at 3:26


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 improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – Saad, user10354138, Alexander Gruber

If this question can be reworded to fit the rules in the help center, please edit the question.







closed as off-topic by Saad, user10354138, Alexander Gruber Dec 4 '18 at 3:26


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 improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – Saad, user10354138, Alexander Gruber

If this question can be reworded to fit the rules in the help center, please edit the question.








  • 1




    $begingroup$
    If there is justice, then $y - y = 0$.
    $endgroup$
    – T. Bongers
    Dec 4 '18 at 0:27














  • 1




    $begingroup$
    If there is justice, then $y - y = 0$.
    $endgroup$
    – T. Bongers
    Dec 4 '18 at 0:27








1




1




$begingroup$
If there is justice, then $y - y = 0$.
$endgroup$
– T. Bongers
Dec 4 '18 at 0:27




$begingroup$
If there is justice, then $y - y = 0$.
$endgroup$
– T. Bongers
Dec 4 '18 at 0:27










1 Answer
1






active

oldest

votes


















1












$begingroup$

Subtraction is defined as a sort of "inverse" of addition, that is, $a - b$ is really shorthand for $a + (-b)$. In this case, $y - y = y + (-y) = 0$. This holds in all rings (at least, under the definitions I'm familiar with).






share|cite|improve this answer









$endgroup$









  • 1




    $begingroup$
    Furthermore, because the field has characteristic 2, $-alpha = alpha$ for each $alpha$ in the field. So for example, $x-y = x + (-y) = x + y = 1$.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 0:32










  • $begingroup$
    what about just $-x$ or $-y$?
    $endgroup$
    – Emma Pascoe
    Dec 4 '18 at 1:05










  • $begingroup$
    @Emma In a field of four elements we have $1+1=0$. Multiplying this by $a$ says that $a+a=(1+1)a=0a=0$. Subtracting $a$ from this gives $$-a=0-a=(a+a)-a=a.$$ This holds for all the elements $a$ of the field.
    $endgroup$
    – Jyrki Lahtonen
    Dec 4 '18 at 4:39




















1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1












$begingroup$

Subtraction is defined as a sort of "inverse" of addition, that is, $a - b$ is really shorthand for $a + (-b)$. In this case, $y - y = y + (-y) = 0$. This holds in all rings (at least, under the definitions I'm familiar with).






share|cite|improve this answer









$endgroup$









  • 1




    $begingroup$
    Furthermore, because the field has characteristic 2, $-alpha = alpha$ for each $alpha$ in the field. So for example, $x-y = x + (-y) = x + y = 1$.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 0:32










  • $begingroup$
    what about just $-x$ or $-y$?
    $endgroup$
    – Emma Pascoe
    Dec 4 '18 at 1:05










  • $begingroup$
    @Emma In a field of four elements we have $1+1=0$. Multiplying this by $a$ says that $a+a=(1+1)a=0a=0$. Subtracting $a$ from this gives $$-a=0-a=(a+a)-a=a.$$ This holds for all the elements $a$ of the field.
    $endgroup$
    – Jyrki Lahtonen
    Dec 4 '18 at 4:39


















1












$begingroup$

Subtraction is defined as a sort of "inverse" of addition, that is, $a - b$ is really shorthand for $a + (-b)$. In this case, $y - y = y + (-y) = 0$. This holds in all rings (at least, under the definitions I'm familiar with).






share|cite|improve this answer









$endgroup$









  • 1




    $begingroup$
    Furthermore, because the field has characteristic 2, $-alpha = alpha$ for each $alpha$ in the field. So for example, $x-y = x + (-y) = x + y = 1$.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 0:32










  • $begingroup$
    what about just $-x$ or $-y$?
    $endgroup$
    – Emma Pascoe
    Dec 4 '18 at 1:05










  • $begingroup$
    @Emma In a field of four elements we have $1+1=0$. Multiplying this by $a$ says that $a+a=(1+1)a=0a=0$. Subtracting $a$ from this gives $$-a=0-a=(a+a)-a=a.$$ This holds for all the elements $a$ of the field.
    $endgroup$
    – Jyrki Lahtonen
    Dec 4 '18 at 4:39
















1












1








1





$begingroup$

Subtraction is defined as a sort of "inverse" of addition, that is, $a - b$ is really shorthand for $a + (-b)$. In this case, $y - y = y + (-y) = 0$. This holds in all rings (at least, under the definitions I'm familiar with).






share|cite|improve this answer









$endgroup$



Subtraction is defined as a sort of "inverse" of addition, that is, $a - b$ is really shorthand for $a + (-b)$. In this case, $y - y = y + (-y) = 0$. This holds in all rings (at least, under the definitions I'm familiar with).







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 4 '18 at 0:29









plattyplatty

3,370320




3,370320








  • 1




    $begingroup$
    Furthermore, because the field has characteristic 2, $-alpha = alpha$ for each $alpha$ in the field. So for example, $x-y = x + (-y) = x + y = 1$.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 0:32










  • $begingroup$
    what about just $-x$ or $-y$?
    $endgroup$
    – Emma Pascoe
    Dec 4 '18 at 1:05










  • $begingroup$
    @Emma In a field of four elements we have $1+1=0$. Multiplying this by $a$ says that $a+a=(1+1)a=0a=0$. Subtracting $a$ from this gives $$-a=0-a=(a+a)-a=a.$$ This holds for all the elements $a$ of the field.
    $endgroup$
    – Jyrki Lahtonen
    Dec 4 '18 at 4:39
















  • 1




    $begingroup$
    Furthermore, because the field has characteristic 2, $-alpha = alpha$ for each $alpha$ in the field. So for example, $x-y = x + (-y) = x + y = 1$.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 0:32










  • $begingroup$
    what about just $-x$ or $-y$?
    $endgroup$
    – Emma Pascoe
    Dec 4 '18 at 1:05










  • $begingroup$
    @Emma In a field of four elements we have $1+1=0$. Multiplying this by $a$ says that $a+a=(1+1)a=0a=0$. Subtracting $a$ from this gives $$-a=0-a=(a+a)-a=a.$$ This holds for all the elements $a$ of the field.
    $endgroup$
    – Jyrki Lahtonen
    Dec 4 '18 at 4:39










1




1




$begingroup$
Furthermore, because the field has characteristic 2, $-alpha = alpha$ for each $alpha$ in the field. So for example, $x-y = x + (-y) = x + y = 1$.
$endgroup$
– Daniel Schepler
Dec 4 '18 at 0:32




$begingroup$
Furthermore, because the field has characteristic 2, $-alpha = alpha$ for each $alpha$ in the field. So for example, $x-y = x + (-y) = x + y = 1$.
$endgroup$
– Daniel Schepler
Dec 4 '18 at 0:32












$begingroup$
what about just $-x$ or $-y$?
$endgroup$
– Emma Pascoe
Dec 4 '18 at 1:05




$begingroup$
what about just $-x$ or $-y$?
$endgroup$
– Emma Pascoe
Dec 4 '18 at 1:05












$begingroup$
@Emma In a field of four elements we have $1+1=0$. Multiplying this by $a$ says that $a+a=(1+1)a=0a=0$. Subtracting $a$ from this gives $$-a=0-a=(a+a)-a=a.$$ This holds for all the elements $a$ of the field.
$endgroup$
– Jyrki Lahtonen
Dec 4 '18 at 4:39






$begingroup$
@Emma In a field of four elements we have $1+1=0$. Multiplying this by $a$ says that $a+a=(1+1)a=0a=0$. Subtracting $a$ from this gives $$-a=0-a=(a+a)-a=a.$$ This holds for all the elements $a$ of the field.
$endgroup$
– Jyrki Lahtonen
Dec 4 '18 at 4:39





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