In a Euclidean domain's division with remainders, is $r=0$ if $t$ divides $s$?












1












$begingroup$


A Euclidean domain $D$ has a function $F$ from nonzero elements of $D$ to nonnegative integers that makes division with remainder possible in $D$: Let $D$ have elements $t$ and $s$, and $t$ is nonzero. Then $D$ has elements $q$ and $r$ for which $s = tq + r$, and if the remainder $r$ is nonzero too, then $F(t) > F(r)$. If $r$ happens to be zero, then $t$ divides $s$ because $s=tq$. If $t$ happens to divides $s$, then is $r$ zero? If $t$ divides $s$, then $s = ut$ for an element $u$ in $D$. Then $r=t(u-q)$ is an element of the ideal generated by $t$, so the ideal generated by $r$ is contained in the ideal $(t)$.



Do any of these mean $r=0$?



We have $t$ divides $r$, which is unusual for nonzero remainders, but, unlike with the Euclidean domain of the integers $mathbb Z$, I don't see the precise contradiction for a general Euclidean domain $D$. Bernard poses a good question. Usually, the $F$ that allows us to deduce $r=0$.



Something that might help: Can we deduce the existence of a function $G$ that satisfies $G(p) le G(pv)$ and $G(p)=0$ if and only if $p=0$?



Thanks, and have a happy new year!










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  • $begingroup$
    Do you suppose that you will stop editing your question eventually?
    $endgroup$
    – José Carlos Santos
    Dec 31 '18 at 16:55












  • $begingroup$
    @JoséCarlosSantos It wasn't working. I stopped editing already.
    $endgroup$
    – Ekhin Taylor R. Wilson
    Dec 31 '18 at 16:56










  • $begingroup$
    What is $F$ in this context?
    $endgroup$
    – Bernard
    Dec 31 '18 at 17:25










  • $begingroup$
    @Bernard any function from nonzero elements of D to nonnegative integers for which the division with remainder is possible. What's the difference if I use the other definition of F, for which $F(a) le F(ab)$?
    $endgroup$
    – Ekhin Taylor R. Wilson
    Dec 31 '18 at 17:31












  • $begingroup$
    Any function, really?
    $endgroup$
    – Bernard
    Dec 31 '18 at 17:32
















1












$begingroup$


A Euclidean domain $D$ has a function $F$ from nonzero elements of $D$ to nonnegative integers that makes division with remainder possible in $D$: Let $D$ have elements $t$ and $s$, and $t$ is nonzero. Then $D$ has elements $q$ and $r$ for which $s = tq + r$, and if the remainder $r$ is nonzero too, then $F(t) > F(r)$. If $r$ happens to be zero, then $t$ divides $s$ because $s=tq$. If $t$ happens to divides $s$, then is $r$ zero? If $t$ divides $s$, then $s = ut$ for an element $u$ in $D$. Then $r=t(u-q)$ is an element of the ideal generated by $t$, so the ideal generated by $r$ is contained in the ideal $(t)$.



Do any of these mean $r=0$?



We have $t$ divides $r$, which is unusual for nonzero remainders, but, unlike with the Euclidean domain of the integers $mathbb Z$, I don't see the precise contradiction for a general Euclidean domain $D$. Bernard poses a good question. Usually, the $F$ that allows us to deduce $r=0$.



Something that might help: Can we deduce the existence of a function $G$ that satisfies $G(p) le G(pv)$ and $G(p)=0$ if and only if $p=0$?



Thanks, and have a happy new year!










share|cite|improve this question











$endgroup$












  • $begingroup$
    Do you suppose that you will stop editing your question eventually?
    $endgroup$
    – José Carlos Santos
    Dec 31 '18 at 16:55












  • $begingroup$
    @JoséCarlosSantos It wasn't working. I stopped editing already.
    $endgroup$
    – Ekhin Taylor R. Wilson
    Dec 31 '18 at 16:56










  • $begingroup$
    What is $F$ in this context?
    $endgroup$
    – Bernard
    Dec 31 '18 at 17:25










  • $begingroup$
    @Bernard any function from nonzero elements of D to nonnegative integers for which the division with remainder is possible. What's the difference if I use the other definition of F, for which $F(a) le F(ab)$?
    $endgroup$
    – Ekhin Taylor R. Wilson
    Dec 31 '18 at 17:31












  • $begingroup$
    Any function, really?
    $endgroup$
    – Bernard
    Dec 31 '18 at 17:32














1












1








1


1



$begingroup$


A Euclidean domain $D$ has a function $F$ from nonzero elements of $D$ to nonnegative integers that makes division with remainder possible in $D$: Let $D$ have elements $t$ and $s$, and $t$ is nonzero. Then $D$ has elements $q$ and $r$ for which $s = tq + r$, and if the remainder $r$ is nonzero too, then $F(t) > F(r)$. If $r$ happens to be zero, then $t$ divides $s$ because $s=tq$. If $t$ happens to divides $s$, then is $r$ zero? If $t$ divides $s$, then $s = ut$ for an element $u$ in $D$. Then $r=t(u-q)$ is an element of the ideal generated by $t$, so the ideal generated by $r$ is contained in the ideal $(t)$.



Do any of these mean $r=0$?



We have $t$ divides $r$, which is unusual for nonzero remainders, but, unlike with the Euclidean domain of the integers $mathbb Z$, I don't see the precise contradiction for a general Euclidean domain $D$. Bernard poses a good question. Usually, the $F$ that allows us to deduce $r=0$.



Something that might help: Can we deduce the existence of a function $G$ that satisfies $G(p) le G(pv)$ and $G(p)=0$ if and only if $p=0$?



Thanks, and have a happy new year!










share|cite|improve this question











$endgroup$




A Euclidean domain $D$ has a function $F$ from nonzero elements of $D$ to nonnegative integers that makes division with remainder possible in $D$: Let $D$ have elements $t$ and $s$, and $t$ is nonzero. Then $D$ has elements $q$ and $r$ for which $s = tq + r$, and if the remainder $r$ is nonzero too, then $F(t) > F(r)$. If $r$ happens to be zero, then $t$ divides $s$ because $s=tq$. If $t$ happens to divides $s$, then is $r$ zero? If $t$ divides $s$, then $s = ut$ for an element $u$ in $D$. Then $r=t(u-q)$ is an element of the ideal generated by $t$, so the ideal generated by $r$ is contained in the ideal $(t)$.



Do any of these mean $r=0$?



We have $t$ divides $r$, which is unusual for nonzero remainders, but, unlike with the Euclidean domain of the integers $mathbb Z$, I don't see the precise contradiction for a general Euclidean domain $D$. Bernard poses a good question. Usually, the $F$ that allows us to deduce $r=0$.



Something that might help: Can we deduce the existence of a function $G$ that satisfies $G(p) le G(pv)$ and $G(p)=0$ if and only if $p=0$?



Thanks, and have a happy new year!







abstract-algebra euclidean-domain






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share|cite|improve this question













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edited Jan 20 at 9:27









user26857

39.3k124183




39.3k124183










asked Dec 31 '18 at 16:53









Ekhin Taylor R. WilsonEkhin Taylor R. Wilson

558




558












  • $begingroup$
    Do you suppose that you will stop editing your question eventually?
    $endgroup$
    – José Carlos Santos
    Dec 31 '18 at 16:55












  • $begingroup$
    @JoséCarlosSantos It wasn't working. I stopped editing already.
    $endgroup$
    – Ekhin Taylor R. Wilson
    Dec 31 '18 at 16:56










  • $begingroup$
    What is $F$ in this context?
    $endgroup$
    – Bernard
    Dec 31 '18 at 17:25










  • $begingroup$
    @Bernard any function from nonzero elements of D to nonnegative integers for which the division with remainder is possible. What's the difference if I use the other definition of F, for which $F(a) le F(ab)$?
    $endgroup$
    – Ekhin Taylor R. Wilson
    Dec 31 '18 at 17:31












  • $begingroup$
    Any function, really?
    $endgroup$
    – Bernard
    Dec 31 '18 at 17:32


















  • $begingroup$
    Do you suppose that you will stop editing your question eventually?
    $endgroup$
    – José Carlos Santos
    Dec 31 '18 at 16:55












  • $begingroup$
    @JoséCarlosSantos It wasn't working. I stopped editing already.
    $endgroup$
    – Ekhin Taylor R. Wilson
    Dec 31 '18 at 16:56










  • $begingroup$
    What is $F$ in this context?
    $endgroup$
    – Bernard
    Dec 31 '18 at 17:25










  • $begingroup$
    @Bernard any function from nonzero elements of D to nonnegative integers for which the division with remainder is possible. What's the difference if I use the other definition of F, for which $F(a) le F(ab)$?
    $endgroup$
    – Ekhin Taylor R. Wilson
    Dec 31 '18 at 17:31












  • $begingroup$
    Any function, really?
    $endgroup$
    – Bernard
    Dec 31 '18 at 17:32
















$begingroup$
Do you suppose that you will stop editing your question eventually?
$endgroup$
– José Carlos Santos
Dec 31 '18 at 16:55






$begingroup$
Do you suppose that you will stop editing your question eventually?
$endgroup$
– José Carlos Santos
Dec 31 '18 at 16:55














$begingroup$
@JoséCarlosSantos It wasn't working. I stopped editing already.
$endgroup$
– Ekhin Taylor R. Wilson
Dec 31 '18 at 16:56




$begingroup$
@JoséCarlosSantos It wasn't working. I stopped editing already.
$endgroup$
– Ekhin Taylor R. Wilson
Dec 31 '18 at 16:56












$begingroup$
What is $F$ in this context?
$endgroup$
– Bernard
Dec 31 '18 at 17:25




$begingroup$
What is $F$ in this context?
$endgroup$
– Bernard
Dec 31 '18 at 17:25












$begingroup$
@Bernard any function from nonzero elements of D to nonnegative integers for which the division with remainder is possible. What's the difference if I use the other definition of F, for which $F(a) le F(ab)$?
$endgroup$
– Ekhin Taylor R. Wilson
Dec 31 '18 at 17:31






$begingroup$
@Bernard any function from nonzero elements of D to nonnegative integers for which the division with remainder is possible. What's the difference if I use the other definition of F, for which $F(a) le F(ab)$?
$endgroup$
– Ekhin Taylor R. Wilson
Dec 31 '18 at 17:31














$begingroup$
Any function, really?
$endgroup$
– Bernard
Dec 31 '18 at 17:32




$begingroup$
Any function, really?
$endgroup$
– Bernard
Dec 31 '18 at 17:32










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