Find maximal ideals in semi local ring with singular












0












$begingroup$


I am trying to analyze the normalization $N$ of a local ring $A_{mathfrak{m}}$ of a variety with Singular. The normalization (integral closure in its total ring of fractions) is semi-local with its maximal ideals lying over $mathfrak{m}A_{mathfrak{m}}$.



According to
https://www.singular.uni-kl.de/Manual/4-0-3/sing_1270.htm#SEC1345
I can calculate a normalization of a local ring $k[x_1, ldots x_n]_{(0)}/I_{(0)}$ and represent it (if i understood correctly) as a factor ring of a polynomial ring $B[y_1, ldots, y_s]$, where $B = k[x_1, ldots x_n]_{(0)}$.



I am doing it like this



LIB "normal.lib";

ring r=0,(x,y),ds;
ideal I = y^2 - x^2*(x+1);
list nor = normal(I);

def R = nor[1][1];
setring R;
norid;
R;


How would I go about finding the maximal ideals in this factor ring and how can they be represented in Singular. For example I would like to know how many there are (for more general examples than this simple node) and if $mathfrak{n}$ is one of those ideals, how can I get to $N_{mathfrak{n}}$. Is this possible? I am aware that this is not a really specific question, sorry. I have unfortunately just a limited knowledge of working with Singular and local orderings. A small hint or a pointer to some resources would be greatly appreciated.










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$endgroup$












  • $begingroup$
    I don't know how to do it in Singular. But if you have a particular maximal ideal in mind, then extend this to the normalization and compute its associated primes in the normalization. Those are the maximal ideals lying over the one you extended.
    $endgroup$
    – Youngsu
    Nov 28 '18 at 21:28
















0












$begingroup$


I am trying to analyze the normalization $N$ of a local ring $A_{mathfrak{m}}$ of a variety with Singular. The normalization (integral closure in its total ring of fractions) is semi-local with its maximal ideals lying over $mathfrak{m}A_{mathfrak{m}}$.



According to
https://www.singular.uni-kl.de/Manual/4-0-3/sing_1270.htm#SEC1345
I can calculate a normalization of a local ring $k[x_1, ldots x_n]_{(0)}/I_{(0)}$ and represent it (if i understood correctly) as a factor ring of a polynomial ring $B[y_1, ldots, y_s]$, where $B = k[x_1, ldots x_n]_{(0)}$.



I am doing it like this



LIB "normal.lib";

ring r=0,(x,y),ds;
ideal I = y^2 - x^2*(x+1);
list nor = normal(I);

def R = nor[1][1];
setring R;
norid;
R;


How would I go about finding the maximal ideals in this factor ring and how can they be represented in Singular. For example I would like to know how many there are (for more general examples than this simple node) and if $mathfrak{n}$ is one of those ideals, how can I get to $N_{mathfrak{n}}$. Is this possible? I am aware that this is not a really specific question, sorry. I have unfortunately just a limited knowledge of working with Singular and local orderings. A small hint or a pointer to some resources would be greatly appreciated.










share|cite|improve this question









$endgroup$












  • $begingroup$
    I don't know how to do it in Singular. But if you have a particular maximal ideal in mind, then extend this to the normalization and compute its associated primes in the normalization. Those are the maximal ideals lying over the one you extended.
    $endgroup$
    – Youngsu
    Nov 28 '18 at 21:28














0












0








0





$begingroup$


I am trying to analyze the normalization $N$ of a local ring $A_{mathfrak{m}}$ of a variety with Singular. The normalization (integral closure in its total ring of fractions) is semi-local with its maximal ideals lying over $mathfrak{m}A_{mathfrak{m}}$.



According to
https://www.singular.uni-kl.de/Manual/4-0-3/sing_1270.htm#SEC1345
I can calculate a normalization of a local ring $k[x_1, ldots x_n]_{(0)}/I_{(0)}$ and represent it (if i understood correctly) as a factor ring of a polynomial ring $B[y_1, ldots, y_s]$, where $B = k[x_1, ldots x_n]_{(0)}$.



I am doing it like this



LIB "normal.lib";

ring r=0,(x,y),ds;
ideal I = y^2 - x^2*(x+1);
list nor = normal(I);

def R = nor[1][1];
setring R;
norid;
R;


How would I go about finding the maximal ideals in this factor ring and how can they be represented in Singular. For example I would like to know how many there are (for more general examples than this simple node) and if $mathfrak{n}$ is one of those ideals, how can I get to $N_{mathfrak{n}}$. Is this possible? I am aware that this is not a really specific question, sorry. I have unfortunately just a limited knowledge of working with Singular and local orderings. A small hint or a pointer to some resources would be greatly appreciated.










share|cite|improve this question









$endgroup$




I am trying to analyze the normalization $N$ of a local ring $A_{mathfrak{m}}$ of a variety with Singular. The normalization (integral closure in its total ring of fractions) is semi-local with its maximal ideals lying over $mathfrak{m}A_{mathfrak{m}}$.



According to
https://www.singular.uni-kl.de/Manual/4-0-3/sing_1270.htm#SEC1345
I can calculate a normalization of a local ring $k[x_1, ldots x_n]_{(0)}/I_{(0)}$ and represent it (if i understood correctly) as a factor ring of a polynomial ring $B[y_1, ldots, y_s]$, where $B = k[x_1, ldots x_n]_{(0)}$.



I am doing it like this



LIB "normal.lib";

ring r=0,(x,y),ds;
ideal I = y^2 - x^2*(x+1);
list nor = normal(I);

def R = nor[1][1];
setring R;
norid;
R;


How would I go about finding the maximal ideals in this factor ring and how can they be represented in Singular. For example I would like to know how many there are (for more general examples than this simple node) and if $mathfrak{n}$ is one of those ideals, how can I get to $N_{mathfrak{n}}$. Is this possible? I am aware that this is not a really specific question, sorry. I have unfortunately just a limited knowledge of working with Singular and local orderings. A small hint or a pointer to some resources would be greatly appreciated.







algebraic-geometry commutative-algebra localization singularity formal-completions






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asked Nov 28 '18 at 17:38









pyrogenpyrogen

714




714












  • $begingroup$
    I don't know how to do it in Singular. But if you have a particular maximal ideal in mind, then extend this to the normalization and compute its associated primes in the normalization. Those are the maximal ideals lying over the one you extended.
    $endgroup$
    – Youngsu
    Nov 28 '18 at 21:28


















  • $begingroup$
    I don't know how to do it in Singular. But if you have a particular maximal ideal in mind, then extend this to the normalization and compute its associated primes in the normalization. Those are the maximal ideals lying over the one you extended.
    $endgroup$
    – Youngsu
    Nov 28 '18 at 21:28
















$begingroup$
I don't know how to do it in Singular. But if you have a particular maximal ideal in mind, then extend this to the normalization and compute its associated primes in the normalization. Those are the maximal ideals lying over the one you extended.
$endgroup$
– Youngsu
Nov 28 '18 at 21:28




$begingroup$
I don't know how to do it in Singular. But if you have a particular maximal ideal in mind, then extend this to the normalization and compute its associated primes in the normalization. Those are the maximal ideals lying over the one you extended.
$endgroup$
– Youngsu
Nov 28 '18 at 21:28










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