Minimal free resolutions for certain affine monomial curves
|
|
- Melvyn Burke
- 5 years ago
- Views:
Transcription
1 Contemporary Mathematics Volume 555, 11 Minimal free resolutions for certain affine monomial curves Philippe Gimenez, Indranath Sengupta, and Hema Srinivasan This paper is dedicated to Wolmer V Vasconcelos Abstract Given an arbitrary field and an arithmetic sequence of positive integers m < < m n, we consider the affine monomial curve in A n+1 parameterized by X = t m,, = t m n In this paper, we conjecture that the Betti numbers of its coordinate ring are completely determined by n and the value of m modulo n We first show that the defining ideal of the monomial curve can be written as a sum of two determinantal ideals Using this fact, we describe the minimal free resolution of the coordinate ring in the following three cases: when m 1 mod n (determinantal, when m n mod n (almost determinantal, and when m mod n and n =4 (Gorenstein of codimension 4 Introduction Let denote an arbitrary field and R be the polynomial ring [X,, ] Consider the -algebra homomorphism ϕ : R [t] givenbyϕ(x i =t m i, i =,,n Then the ideal P := er ϕ R is the defining ideal of the monomial curve in A n+1 given by the parametrization X = t m,, = t m n The-algebra of the semigroup Γ N generated by m,,m n is [Γ] := [t m,,t m n ] R/P, which is one-dimensional and P is a perfect ideal of codimension n Itiswellnown that P is minimally generated by binomials Moreover, P is a homogeneous ideal and [Γ] is the homogeneous coordinate ring if we give weight m i to the variables X i Henceforth, homogeneous and graded would mean homogeneous and graded with respect to this weighted graduation Assume now that the positive integers m,,m n satisfy the following properties: 1991 Mathematics Subject Classification Primary 13D; Secondary 13A, 13C4 Key words and phrases Monomial curves, arithmetic sequences, determinantal ideals, Betti numbers, minimal free resolutions The first author is partially supported by MTM1-79-C-, Ministerio de Educación y Ciencia, Spain The second author thans DST, Government of India for financial support for the project Computational Commutative Algebra, reference no SR/S4/MS: 614/9, and for the BOYSCAST 3 Fellowship This collaboration is the outcome of the second author s visits to the University of Missouri, Columbia, USA during Fall 7 and to the University of Valladolid, SPAIN for two months in 9 He thans both the institutions for their support 1 c 11 American Mathematical Society 87
2 88 PHILIPPE GIMENEZ, INDRANATH SENGUPTA, AND HEMA SRINIVASAN (i gcd (m,,m n =1; (ii <m < <m n and m i = m + id for every i [1,n], ie, the integers form an arithmetic progression with common difference d; (iii m,,m n generate the semigroup Γ := Nm i minimally, where N = {, 1,,}, ie, m j / i n; i j i n Nm i for every i [,n] Definition 1 A sequence of positive intergers (m =m,,m n is called an arithmetic sequence if it satisfies the conditions (i,(ii and (iii above Let us write m = an + b such that a, b are positive integers and b [1,n] Note that b [1,n] and condition (iii on m,,m n ensures that a 1; otherwise m = b and m b = m + bd =(1+db contradicts minimally condition (iii Let (m =m,,m n be an arithmetic sequence We say that the monomial curve in A n+1 parameterized by X = t m,, = t m n is the monomial curve associated to the arithmetic sequence (m and denote it by C(m A minimal binomial generating set for the defining ideal P of C(m was given in [P], and it was rewritten in [MS] toprovethatp is not a complete intersection if n 3 An explicit formula for the type of [Γ] is given in [PS, Corollary 6] under a more general assumption of almost arithmetic sequence on the integers (m =m,,m n and it follows from this result that if (m =m,,m n is an arithmetic sequence then [Γ] is Gorenstein if and only if b = In this paper, we prove in Theorem 11 that ideal P has the special structure that it can be written as a sum of two determinantal ideals, one of them being the defining ideal of the rational normal curve We exploit this structure to construct an explicit minimal free resolution of the graded ideal P, in the cases when m 1orn modulo n, andwhenm modulo n and n 4 Note that a minimal free resolution for P had already been constructed for n = 3 in [S1] usingagröbner basis for P In [S] the following question was posed : do the total Betti numbers of P depend only on the integer m modulo n? In this article, we answer this question in affirmative for the above cases This question will be addressed in general in our wor in progress [GSS] 1 The defining ideal By [P] and[ms], one nows that the number of elements in a minimal set of generators of the ideal P depends only on m modulo n Our first result shows that P has an additional structure that will be helpful in the sequel Theorem 11 Let (m =m,m n be an arithmetic sequence and P be the defining ideal of the monomial curve C(m associated to m Then P = I ( X X 1 1 X a n X b +I X 1 X ( X b Proof It is nown from [P] and[ms], that P is minimally generated by the following set of binomials {δ ij i<j n 1} {Δ 1,j j =,,n+ b}, such that δ i, j := X i X j+1 X j X i+1, i<j n 1
3 MINIMAL FREE RESOLUTIONS FOR CERTAIN AFFINE MONOMIAL CURVES 893 and Δ 1,j := X b+j Xn a X j, j =,,n+ b The binomials δ ij are precisely the ( n the matrix A = ( X X 1 X 1 X generators of the ideal of minors of 1 On the other hand, the binomials Δ 1,j are the minors from the first and the jth column of the matrix ( X a n X b B = X b Since the rest of the minors of B are already in the ideal I (A, one gets that P = P 1 + P,whereP 1 and P are the determinatal ideals generated by the maximal minors of the matrices A and B respectively The actual generators also depend only on the first term m, the common difference d and the length n of the arithmetic sequence (m This is no surprise as these three numbers do determine the arithmetic sequence However, we also have that the number of minimal generators of the ideal P is ( n + n b + 1 and hence only depends on n and b We conjecture that the following statement is true: Conjecture 1 Let (m =m,,m n be an arithmetic sequence Then all the Betti numbers of the homogeneous coordinate ring [Γ] of the affine monomial curve C(m ina n+1 associated to (m are determined by n and the value of m modulo n In the next section, we discuss the conjecture in cases b = 1, andn and construct a minimal resolution when b = 1orn using the aforesaid determinantal structures In the first special case, b =1,wehavethatP is a determinantal ideal The second special case is b = n, thatiswhen ( X a n X B := and therefore the ideal P is the principal ideal generated by +1 Xn a+1 The third special case is b =, that is when [Γ] is Gorenstein In this case, we wiil give the Betti numbers when the codimension n is 4 The minimal resolution 1 First case: determinantal (m 1 modulo n Assume that b =1 In this case, ( X a n X 1 B := X 1 and hence I (A I (B Thus, P = P is a determinantal ideal of codimension n generated by the maximal minors of the (n +1 matrix B Therefore, the homogeneous coordinate ring [Γ] is minimally resolved by the Eagon-Northcott complex The resolution is given by n+1 R n+1 D n 1 (R 3 R n+1 D 1 (R R n+1 R [Γ],
4 49 PHILIPPE GIMENEZ, INDRANATH SENGUPTA, AND HEMA SRINIVASAN such that D s 1 (R =(S s 1 (R denotes the R-module which is the dual of the symmetric algebra of R and the module S s 1 (R isfreeofrans, with a basis the set of monomials of total degree (s 1 in λ, λ 1 (symbols representing basis elements of R Therefore, up to an identification, D s 1 (R =(S s 1 (R is a free R-module of ran s, with a basis {λ v λv 1 1 v,v 1 N,v + v 1 = s 1} For every s =1,,n,letG s denote s+1 R n+1 D s 1 (R, which is a R-free module of ran s ( n+1 s+1 generated by the basis elements (ei1 e λv is+1 λv 1 1, for every 1 i 1 <i < <i s+1 n +1andv,v 1 N,v + v 1 = s 1 The differentials d s : G s G s 1 are given by the following formulae: d 1 (e i1 e i =X i1 1X i X i 1X i1, 1 i 1 <i n +1, and for s =,,n and 1 i 1 < <i s+1 n +1, s+1 d s ((e i1 e is+1 λ v λv 1 1 = ( 1 j+1 X ij 1((e i1 ê ij e is+1 λ v 1 j=1 λ v 1 1 s+1 + ( 1 j+1 X ij ((e i1 ê ij e is+1 λ v λv j=1 such that summands on the right hand side involve only non-negative powers of λ and λ 1 We have therefore proved the following: Theorem 1 The minimal free resolution of the homogeneous coordinate ring [Γ] of the affine monomial curve C(m in A n+1 associated to the arithmetic sequence of integers (m =m,,m n with the property m 1 modulo n is R n d n R (n 1( n+1 n d n 1 R s(n+1 s+1 d s R (n+1 d 1 R ϕ [Γ] In particular, the Betti numbers are β =1and β s = s ( n+1 s+1 for every s [1,n] Remar The case a =1(andb = 1 corresponds to semigroups Γ of maximal embedding dimension, ie, those semigroups such that the inequality m(γ e(γ is an equality, being m(γ := m = an + b and e(γ := n +1 the multiplicity and the embedding dimension respectively Note that the above argument gives indeed the graded resolution (with respect to the grading given by deg(x i =m i = m + id: Corollary 3 Under the hypothesis of Theorem 1, the minimal graded free resolution of [Γ] is given by
5 MINIMAL FREE RESOLUTIONS FOR CERTAIN AFFINE MONOMIAL CURVES 915 d n ( n n +1 R( (a + n + dm + d d ( n 1 ( n +1 R( nm + d d ( d n 1 n 1 R( (a + d + n 1m + d r i 1 r 1 <r n 1 n i=1 d n 1 d s 1 r 1 <<r s n 1 r 1 <<r s 1 n ( s 1 R( sm + d ( s 1 s d r i i=1 s 1 R( (a + s 1+dm + d i=1 r i d d s 1 d 1 r 1 <r n d 1 ϕ R [Γ] R( m (r 1 + r 1d ( n 1 R( (a +1+dm d Second case: almost determinantal (m n modulo n In this case, we show that [Γ] can be resolved minimally by a mapping cone using the resolution for R/P 1, which is the homogeneous coordinate ring of the rational normal curve The minimal free resolution for R/P 1 is the Eagon-Northcott complex given by E : n R n (S n (R R n (S (R R R/P 1 Since E s := s+1 R n (S s 1 (R = R s( n s+1, for every s =1,,n 1, E := R = R, theresolutione taes the form R n 1 R (n ( n n 1 R s( n s+1 R ( n R R/P1 The differentials d 1 s : E s E s 1 are defined similarly as d s above, for every s =1,,n 1 = Now consider the short exact sequence of R-modules R/(P 1 :Δ 1, Δ 1, R/P 1 R/P 1 +(Δ 1, where the map R/(P 1 :Δ 1, Δ 1, R/P 1 is the multiplication by Δ 1, The colon ideal (P 1 :Δ 1, is exactly equal to P 1,sinceP 1 is a prime ideal and Δ 1, P 1, being a part of a minimal generating set for the ideal P = P 1 + P Therefore, the above short exact sequence becomes, R/P 1 ( (a + d +1m Δ 1, R/P 1 R/P 1 +(Δ 1,,
6 69 PHILIPPE GIMENEZ, INDRANATH SENGUPTA, AND HEMA SRINIVASAN taing gradation into account We define the graded complex homomorphism ψ : E( (a + d +1m E as the multiplication by Δ 1,, which is a lift of the map R/P 1 ( (a + d +1m Δ 1, R/P 1 In fact, the complex homomorphism ψ is simply multiplication by Δ 1, The mapping cone F(ψ is given by the free modules F s = E s 1 E s = R (s 1(n s R s( s+1 n, for every s =,,n (with E 1 = E n = and the differentials d s : F s F s 1, defined as d s(x, y =(ψ s 1 (y+d 1 s(x, d 1 s 1(y, for every s =1,,n R/P 1 +(Δ 1, is resolved by the mapping cone F(ψ It is minimal because each of the maps in ψ is of positive degree and the resolution E is minimal Hence, the mapping cone F(ψ is the minimal free resolution of the homogeneous coordinate ring [Γ] = R/P We have therefore proved the following: Theorem 4 The minimal free resolution of the homogeneous coordinate ring [Γ] of the affine monomial curve C(m in A n+1 associated to the arithmetic sequence of integers (m =m,,m n with the property m n modulo n is R n 1 d n R (n ( n 1+(n 1 n d n 1 R 1+(n d 1 R ϕ [Γ] In particular, the Betti numbers are β =1, β 1 =1+ ( n for every s [,n] and βs =(s 1 ( n s ( +s n s+1 As in Section 1, one can be more precise and give the graded resolution First note that the graded minimal resolution of P 1 is given by n 1 ( n +1 d 1 n 1 R( nm + d d ( d 1 s s 1 R( sm + d r i d d 1 1 r 1 <<r s n 1 r 1 <r n R( m (r 1 + r 1d d 1 s 1 d 1 1 R R/P 1
7 MINIMAL FREE RESOLUTIONS FOR CERTAIN AFFINE MONOMIAL CURVES 937 Corollary 5 Under the hypothesis of Theorem 4, the minimal graded free resolution of [Γ] is given by d n n 1 ( n +1 R( (a + n + d +1m + d d ( n 1 ( n +1 R( nm + d d ( d n R( (a + n + dm + d r i 1 r 1 <<r n 1 n d n 1 d s 1 r 1 <<r s n ( s 1 d R( sm + d r i ( s 1 r 1 <<r s 1 n d R( (a + s + dm + d r i d s 1 d 1 r 1 <r n R( m (r 1 + r 1d R( (a +1+dm d 1 R ϕ [Γ] 3 Third case: Gorenstein of codimension 4 (m modulo n and n =4 When b =, the ideal P is Gorenstein of height n and hence the first and the last Betti numbers are nown This provides a very interesting family of Gorenstein ideals of height n generated by (n 1(n +/ binomials When n =,P is a complete intersection and when n =3,P is the ideal of 4 4pfaffiansofa5 5 sew symmetric matrix For n = 4, the ideal P is a height 4 Gorenstein ideal minimally generated by 9 elements and therefore has Betti numbers 9, 16, 9 and 1 In fact, we can show that with this weighted grading, the shifts in a graded resolution of R/P are as follows: Theorem 6 Given two non-negative integers a and d, consider the monomial curve C(m in A 5 associated to the arithmetic sequence (m =4a +, 4a ++ d, 4a ++d, 4a ++3d, 4a ++4d Setq := a +1 Then the defining ideal P of C(m is a height four Gorenstein ideal whose minimal graded free resolution is
8 894 PHILIPPE GIMENEZ, INDRANATH SENGUPTA, AND HEMA SRINIVASAN R( q(q +d +9 9d ( 9 ( 7 R( 8q d R( q(q +d +5 d R( q(q +d +5 5d =7 =3 ( 7 R( 6q 4d R ( 6q d R( 6q 8d R( q(q +d +3 d =5 ( 4 R ( q(q +d +3 d R( q(q +d +3 5d = ( 6 ( R( 4q d R( 4q 4d R( q(q +d +1 d P = Proof We now that P is Gorenstein of height 4 and by Theorem 11, it is generated by the minors of A and B, where ( X X 1 X X 3 A = X 1 X X3 and ( X a 4 B = = X 4 X X 1 X X X 3 X 4 Moreover, the 9 minimal generators of P are the six minors of A whose degrees are m + d, =, 3, 4, 4, 5, 6form := 4a + = (a +1 = q, and the 3 minors of B involving the first column which are of degrees m (a + d +1+d, =, 1, Note that for both determinantal ideals I (A andi (B, the Eagon-Northcott complex provides a minimal resolution The 8 determinantal relations from the Eagon-Northcott resolution of I (A and the 6 determinantal relations from the Eagon-Northcott resolution of I (B involving the first column will necessarily be among the 16 minimal syzygies of P The degrees of the other two relations are determined by the symmetry of the resolution Thus the remaining two relations must be of degrees q(q +3+(q +d and q(q +3+(q +4d This determines the rest of the degrees in the resolution We note that when d = 1, this ideal can never be determinantal even though it is height 4 and generated by 9 elements That is, this ideal is not the ideal of minors of a 3 3 matrix for sum of the degrees of such an ideal must be even For in this case, the ideal is generated by 9 elements whose degrees add up to 7d + m Since m is even, this number is odd whenever d is odd Hence if d is odd, it cannot be a determinantal ideal However, it is not clear if it can be determinantal for even values of d Of course, the conjecture only says that the Betti numbers are determined by b References [GSS] P Gimenez, I Sengupta and H Srinivasan, Minimal graded free resolution for monomial curves defined by an arithmetic sequence (11, in progress [MS] A K Maloo and I Sengupta, Criterion for complete intersection of certain monomial curves, in: Advances in Algebra and Geometry (Hyderabad, 1, , Hindustan Boo Agency, New Delhi, 3
9 MINIMAL FREE RESOLUTIONS FOR CERTAIN AFFINE MONOMIAL CURVES 959 [P] D P Patil, Minimal sets of generators for the relation ideals of certain monomial curves, Manuscripta Math 8 ( [PS] D P Patil and I Sengupta, Minimal set of generators for the derivation module of certain monomial curves, Comm Algebra 7(11 ( [S1] I Sengupta, A minimal free resolution for certain monomial curves in A 4, Comm Algebra 31(6 ( [S] I Sengupta, Betti numbers of certain affine monomial curves, In EACA-6 (Sevilla, F-J Castro Jiménez and J-M Ucha Enríquez Eds, ISBN: Department of Algebra, Geometry and Topology, Faculty of Sciences, University of Valladolid, 475 Valladolid, Spain address: pgimenez@agtuvaes School of Mathematical Sciences, RKM Viveananda University, Belur, India Current address: Department of Mathematics, Jadavpur University, Kolata, WB 7 3, India address: senguptaindranath@gmailcom Mathematics Department, University of Missouri, Columbia, MO 6511, USA address: SrinivasanH@missouriedu
On intersections of complete intersection ideals
On intersections of complete intersection ideals Mircea Cimpoeaş I.M.A.R. mircea.cimpoeas@imar.ro joint work with Dumitru Stamate July 7, 2016, I.M.N.S., Levico Terme, Italy Overview 1 Introduction 2 Main
More informationHomogeneous numerical semigroups, their shiftings, and monomial curves of homogeneous type
Homogeneous numerical semigroups, their shiftings, and monomial curves of homogeneous type International Meeting on Numerical Semigroups with Applications July 4 to 8, 2016 Levico Terme, Italy Based on
More informationThe Symmetric Algebra for Certain Monomial Curves 1
International Journal of Algebra, Vol. 5, 2011, no. 12, 579-589 The Symmetric Algebra for Certain Monomial Curves 1 Debasish Mukhopadhyay Acharya Girish Chandra Bose College 35, Scott Lane, Kolkata, WB
More informationarxiv: v2 [math.ac] 1 Jan 2016
arxiv:153.687v [math.ac] 1 Jan 16 MINIMAL GADED FEE ESOLUTIONS FO MONOMIAL CUVES IN A 4 DEFINED BY ALMOST AITHMETIC SEQUENCES ACHINTYA KUMA OY, INDANATH SENGUPTA, AND GAUAB TIPATHI Abstract. Let m = m,m
More informationBETTI NUMBERS AND DEGREE BOUNDS FOR SOME LINKED ZERO-SCHEMES
BETTI NUMBERS AND DEGREE BOUNDS FOR SOME LINKED ZERO-SCHEMES LEAH GOLD, HAL SCHENCK, AND HEMA SRINIVASAN Abstract In [8], Herzog and Srinivasan study the relationship between the graded Betti numbers of
More informationARITHMETICALLY COHEN-MACAULAY BUNDLES ON THREE DIMENSIONAL HYPERSURFACES
ARITHMETICALLY COHEN-MACAULAY BUNDLES ON THREE DIMENSIONAL HYPERSURFACES N. MOHAN KUMAR, A. P. RAO, AND G. V. RAVINDRA Abstract. We prove that any rank two arithmetically Cohen- Macaulay vector bundle
More informationNUMERICAL MONOIDS (I)
Seminar Series in Mathematics: Algebra 2003, 1 8 NUMERICAL MONOIDS (I) Introduction The numerical monoids are simple to define and naturally appear in various parts of mathematics, e.g. as the values monoids
More informationarxiv: v1 [math.ac] 8 Jun 2012
DECOMPOSITION OF MONOMIAL ALGEBRAS: APPLICATIONS AND ALGORITHMS JANKO BÖHM, DAVID EISENBUD, AND MAX J. NITSCHE arxiv:1206.1735v1 [math.ac] 8 Jun 2012 Abstract. Considering finite extensions K[A] K[B] of
More informationLINKAGE CLASSES OF GRADE 3 PERFECT IDEALS
LINKAGE CLASSES OF GRADE 3 PERFECT IDEALS LARS WINTHER CHRISTENSEN, OANA VELICHE, AND JERZY WEYMAN Abstract. While every grade 2 perfect ideal in a regular local ring is linked to a complete intersection
More informationQuadrics Defined by Skew-Symmetric Matrices
International Journal of Algebra, Vol. 11, 2017, no. 8, 349-356 HIKAI Ltd, www.m-hikari.com https://doi.org/10.12988/ija.2017.7942 Quadrics Defined by Skew-Symmetric Matrices Joydip Saha 1, Indranath Sengupta
More informationarxiv:math/ v1 [math.ac] 15 Sep 2002
arxiv:math/0209186v1 [math.ac] 15 Sep 2002 A SIMPLE PROOF OF SOME GENERALIZED PRINCIPAL IDEAL THEOREMS DAVID EISENBUD, CRAIG HUNEKE, AND BERND ULRICH Abstract. Using symmetric algebras we simplify (and
More informationMULTIPLICITIES OF MONOMIAL IDEALS
MULTIPLICITIES OF MONOMIAL IDEALS JÜRGEN HERZOG AND HEMA SRINIVASAN Introduction Let S = K[x 1 x n ] be a polynomial ring over a field K with standard grading, I S a graded ideal. The multiplicity of S/I
More informationA CONSTRUCTION FOR ABSOLUTE VALUES IN POLYNOMIAL RINGS. than define a second approximation V 0
A CONSTRUCTION FOR ABSOLUTE VALUES IN POLYNOMIAL RINGS by SAUNDERS MacLANE 1. Introduction. An absolute value of a ring is a function b which has some of the formal properties of the ordinary absolute
More informationarxiv: v2 [math.ac] 19 Dec 2008
A combinatorial description of monomial algebras arxiv:0810.4836v2 [math.ac] 19 Dec 2008 Ignacio Oeda Universidad de Extremadura Departamento de Matemáticas e-mail: oedamc@unex.es March 22, 2009 Abstract
More informationA degree bound for codimension two lattice ideals
Journal of Pure and Applied Algebra 18 (003) 01 07 www.elsevier.com/locate/jpaa A degree bound for codimension two lattice ideals Leah H. Gold Department of Mathematics, Texas A& M University, College
More informationGORENSTEIN HILBERT COEFFICIENTS. Sabine El Khoury. Hema Srinivasan. 1. Introduction. = (d 1)! xd ( 1) d 1 e d 1
GORENSTEIN HILBERT COEFFICIENTS Sabine El Khoury Department of Mathematics, American University of Beirut, Beirut, Lebanon se24@aubedulb Hema Srinivasan Department of Mathematics, University of Missouri,
More informationDUALITY FOR KOSZUL HOMOLOGY OVER GORENSTEIN RINGS
DUALITY FO KOSZUL HOMOLOGY OVE GOENSTEIN INGS CLAUDIA MILLE, HAMIDEZA AHMATI, AND JANET STIULI Abstract. We study Koszul homology over Gorenstein rings. If an ideal is strongly Cohen-Macaulay, the Koszul
More informationFINITE REGULARITY AND KOSZUL ALGEBRAS
FINITE REGULARITY AND KOSZUL ALGEBRAS LUCHEZAR L. AVRAMOV AND IRENA PEEVA ABSTRACT: We determine the positively graded commutative algebras over which the residue field modulo the homogeneous maximal ideal
More informationRECTANGULAR SIMPLICIAL SEMIGROUPS
RECTANGULAR SIMPLICIAL SEMIGROUPS WINFRIED BRUNS AND JOSEPH GUBELADZE In [3] Bruns, Gubeladze, and Trung define the notion of polytopal semigroup ring as follows. Let P be a lattice polytope in R n, i.
More informationAlgebraic Geometry (Math 6130)
Algebraic Geometry (Math 6130) Utah/Fall 2016. 2. Projective Varieties. Classically, projective space was obtained by adding points at infinity to n. Here we start with projective space and remove a hyperplane,
More informationOn the vanishing of Tor of the absolute integral closure
On the vanishing of Tor of the absolute integral closure Hans Schoutens Department of Mathematics NYC College of Technology City University of New York NY, NY 11201 (USA) Abstract Let R be an excellent
More informationPrime and irreducible elements of the ring of integers modulo n
Prime and irreducible elements of the ring of integers modulo n M. H. Jafari and A. R. Madadi Department of Pure Mathematics, Faculty of Mathematical Sciences University of Tabriz, Tabriz, Iran Abstract
More informationGENERATING FUNCTIONS ASSOCIATED TO FROBENIUS ALGEBRAS
GENERATING FUNCTIONS ASSOCIATED TO FROBENIUS ALGEBRAS JOSEP ÀLVAREZ MONTANER Abstract. We introduce a generating function associated to the homogeneous generators of a graded algebra that measures how
More informationJournal of Algebra 226, (2000) doi: /jabr , available online at on. Artin Level Modules.
Journal of Algebra 226, 361 374 (2000) doi:10.1006/jabr.1999.8185, available online at http://www.idealibrary.com on Artin Level Modules Mats Boij Department of Mathematics, KTH, S 100 44 Stockholm, Sweden
More informationAMS meeting at Georgia Southern University March, Andy Kustin University of South Carolina. I have put a copy of this talk on my website.
The Generic Hilbert-Burch matrix AMS meeting at Georgia Southern University March, 2011 Andy Kustin University of South Carolina I have put a copy of this talk on my website 1 The talk consists of: The
More informationDomination and Independence Numbers of Γ(Z n )
International Mathematical Forum, 3, 008, no. 11, 503-511 Domination and Independence Numbers of Γ(Z n ) Emad E. AbdAlJawad and Hasan Al-Ezeh 1 Department of Mathematics, Faculty of Science Jordan University,
More informationCOURSE SUMMARY FOR MATH 508, WINTER QUARTER 2017: ADVANCED COMMUTATIVE ALGEBRA
COURSE SUMMARY FOR MATH 508, WINTER QUARTER 2017: ADVANCED COMMUTATIVE ALGEBRA JAROD ALPER WEEK 1, JAN 4, 6: DIMENSION Lecture 1: Introduction to dimension. Define Krull dimension of a ring A. Discuss
More informationE. GORLA, J. C. MIGLIORE, AND U. NAGEL
GRÖBNER BASES VIA LINKAGE E. GORLA, J. C. MIGLIORE, AND U. NAGEL Abstract. In this paper, we give a sufficient condition for a set G of polynomials to be a Gröbner basis with respect to a given term-order
More informationNEW CONSTRUCTION OF THE EAGON-NORTHCOTT COMPLEX. Oh-Jin Kang and Joohyung Kim
Korean J Math 20 (2012) No 2 pp 161 176 NEW CONSTRUCTION OF THE EAGON-NORTHCOTT COMPLEX Oh-Jin Kang and Joohyung Kim Abstract The authors [6 introduced the concept of a complete matrix of grade g > 3 to
More informationREFLEXIVE MODULES OVER GORENSTEIN RINGS
REFLEXIVE MODULES OVER GORENSTEIN RINGS WOLMER V. VASCONCELOS1 Introduction. The aim of this paper is to show the relevance of a class of commutative noetherian rings to the study of reflexive modules.
More informationOn the Splitting of MO(2) over the Steenrod Algebra. Maurice Shih
On the Splitting of MO(2) over the Steenrod Algebra Maurice Shih under the direction of John Ullman Massachusetts Institute of Technology Research Science Institute On the Splitting of MO(2) over the Steenrod
More informationIDEALS AND THEIR INTEGRAL CLOSURE
IDEALS AND THEIR INTEGRAL CLOSURE ALBERTO CORSO (joint work with C. Huneke and W.V. Vasconcelos) Department of Mathematics Purdue University West Lafayette, 47907 San Diego January 8, 1997 1 SETTING Let
More informationThe minimal components of the Mayr-Meyer ideals
The minimal components of the Mayr-Meyer ideals Irena Swanson 24 April 2003 Grete Hermann proved in [H] that for any ideal I in an n-dimensional polynomial ring over the field of rational numbers, if I
More informationarxiv: v2 [math.ac] 18 Oct 2018
A NOTE ON LINEAR RESOLUTION AND POLYMATROIDAL IDEALS arxiv:1810.07582v2 [math.ac] 18 Oct 2018 AMIR MAFI AND DLER NADERI Abstract. Let R = K[x 1,..., x n] be the polynomial ring in n variables over a field
More informationMinimal free resolutions of analytic D-modules
Minimal free resolutions of analytic D-modules Toshinori Oaku Department of Mathematics, Tokyo Woman s Christian University Suginami-ku, Tokyo 167-8585, Japan November 7, 2002 We introduce the notion of
More informationManoj K. Keshari 1 and Satya Mandal 2.
K 0 of hypersurfaces defined by x 2 1 +... + x 2 n = ±1 Manoj K. Keshari 1 and Satya Mandal 2 1 Department of Mathematics, IIT Mumbai, Mumbai - 400076, India 2 Department of Mathematics, University of
More informationOn a Generalization of the Coin Exchange Problem for Three Variables
1 3 47 6 3 11 Journal of Integer Sequences, Vol. 9 (006), Article 06.4.6 On a Generalization of the Coin Exchange Problem for Three Variables Amitabha Tripathi Department of Mathematics Indian Institute
More information12. Hilbert Polynomials and Bézout s Theorem
12. Hilbert Polynomials and Bézout s Theorem 95 12. Hilbert Polynomials and Bézout s Theorem After our study of smooth cubic surfaces in the last chapter, let us now come back to the general theory of
More informationRees Algebras of Modules
Rees Algebras of Modules ARON SIMIS Departamento de Matemática Universidade Federal de Pernambuco 50740-540 Recife, PE, Brazil e-mail: aron@dmat.ufpe.br BERND ULRICH Department of Mathematics Michigan
More informationIs Every Secant Variety of a Segre Product Arithmetically Cohen Macaulay? Oeding (Auburn) acm Secants March 6, / 23
Is Every Secant Variety of a Segre Product Arithmetically Cohen Macaulay? Luke Oeding Auburn University Oeding (Auburn) acm Secants March 6, 2016 1 / 23 Secant varieties and tensors Let V 1,..., V d, be
More informationProblems on Minkowski sums of convex lattice polytopes
arxiv:08121418v1 [mathag] 8 Dec 2008 Problems on Minkowski sums of convex lattice polytopes Tadao Oda odatadao@mathtohokuacjp Abstract submitted at the Oberwolfach Conference Combinatorial Convexity and
More informationON THE SUM OF ELEMENT ORDERS OF FINITE ABELIAN GROUPS
ANALELE ŞTIINŢIFICE ALE UNIVERSITĂŢII AL.I. CUZA DIN IAŞI (S.N.) MATEMATICĂ, Tomul...,..., f... DOI: 10.2478/aicu-2013-0013 ON THE SUM OF ELEMENT ORDERS OF FINITE ABELIAN GROUPS BY MARIUS TĂRNĂUCEANU and
More informationPseudo symmetric monomial curves
Pseudo symmetric monomial curves Mesut Şahin HACETTEPE UNIVERSITY Joint work with Nil Şahin (Bilkent University) Supported by Tubitak No: 114F094 IMNS 2016, July 4-8, 2016 Mesut Şahin (HACETTEPE UNIVERSITY)
More informationCONDITIONS FOR THE YONEDA ALGEBRA OF A LOCAL RING TO BE GENERATED IN LOW DEGREES
CONDITIONS FOR THE YONEDA ALGEBRA OF A LOCAL RING TO BE GENERATED IN LOW DEGREES JUSTIN HOFFMEIER AND LIANA M. ŞEGA Abstract. The powers m n of the maximal ideal m of a local Noetherian ring R are known
More informationPrimitive Ideals of Semigroup Graded Rings
Sacred Heart University DigitalCommons@SHU Mathematics Faculty Publications Mathematics Department 2004 Primitive Ideals of Semigroup Graded Rings Hema Gopalakrishnan Sacred Heart University, gopalakrishnanh@sacredheart.edu
More informationINTERVAL PARTITIONS AND STANLEY DEPTH
INTERVAL PARTITIONS AND STANLEY DEPTH CSABA BIRÓ, DAVID M. HOWARD, MITCHEL T. KELLER, WILLIAM. T. TROTTER, AND STEPHEN J. YOUNG Abstract. In this paper, we answer a question posed by Herzog, Vladoiu, and
More informationarxiv: v2 [math.ac] 7 Nov 2017
SYMBOLIC BLOWUP ALGEBAS OF MONOMIAL CUVES IN A 3 DEFINED BY AIHMEIC SEQUENCE CLAE D CUZ arxiv:1708.01374v [math.ac] 7 Nov 017 Abstract. In this paper, we consider monomial curves ina 3 k parameterized
More informationA Classification of Integral Apollonian Circle Packings
A Classification of Integral Apollonian Circle Pacings Tabes Bridges Warren Tai Advised by: Karol Koziol 5 July 011 Abstract We review the basic notions related to Apollonian circle pacings, in particular
More information(1) is an invertible sheaf on X, which is generated by the global sections
7. Linear systems First a word about the base scheme. We would lie to wor in enough generality to cover the general case. On the other hand, it taes some wor to state properly the general results if one
More informationCourse 311: Michaelmas Term 2005 Part III: Topics in Commutative Algebra
Course 311: Michaelmas Term 2005 Part III: Topics in Commutative Algebra D. R. Wilkins Contents 3 Topics in Commutative Algebra 2 3.1 Rings and Fields......................... 2 3.2 Ideals...............................
More informationGroups of Prime Power Order with Derived Subgroup of Prime Order
Journal of Algebra 219, 625 657 (1999) Article ID jabr.1998.7909, available online at http://www.idealibrary.com on Groups of Prime Power Order with Derived Subgroup of Prime Order Simon R. Blackburn*
More informationA family of local rings with rational Poincaré Series
arxiv:0802.0654v1 [math.ac] 5 Feb 2008 A family of local rings with rational Poincaré Series Juan Elias Giuseppe Valla October 31, 2018 Abstract In this note we compute the Poincare Series of almost stretched
More informationMath 711: Lecture of September 7, Symbolic powers
Math 711: Lecture of September 7, 2007 Symbolic powers We want to make a number of comments about the behavior of symbolic powers of prime ideals in Noetherian rings, and to give at least one example of
More informationARITHMETIC PROGRESSIONS IN CYCLES OF QUADRATIC POLYNOMIALS
ARITHMETIC PROGRESSIONS IN CYCLES OF QUADRATIC POLYNOMIALS TIMO ERKAMA It is an open question whether n-cycles of complex quadratic polynomials can be contained in the field Q(i) of complex rational numbers
More informationBinomial Exercises A = 1 1 and 1
Lecture I. Toric ideals. Exhibit a point configuration A whose affine semigroup NA does not consist of the intersection of the lattice ZA spanned by the columns of A with the real cone generated by A.
More informationBP -HOMOLOGY AND AN IMPLICATION FOR SYMMETRIC POLYNOMIALS. 1. Introduction and results
BP -HOMOLOGY AND AN IMPLICATION FOR SYMMETRIC POLYNOMIALS DONALD M. DAVIS Abstract. We determine the BP -module structure, mod higher filtration, of the main part of the BP -homology of elementary 2- groups.
More informationLOCAL COHOMOLOGY MODULES WITH INFINITE DIMENSIONAL SOCLES
LOCAL COHOMOLOGY MODULES WITH INFINITE DIMENSIONAL SOCLES THOMAS MARLEY AND JANET C. VASSILEV Abstract. In this paper we prove the following generalization of a result of Hartshorne: Let T be a commutative
More informationarxiv:math/ v1 [math.ac] 4 Oct 2002
manuscripta mathematica manuscript No. (will be inserted by the editor) Alberto Corso Claudia Polini Bernd Ulrich Core of projective dimension one modules arxiv:math/0210072v1 [math.ac] 4 Oct 2002 Received:
More informationCHOMP ON NUMERICAL SEMIGROUPS
CHOMP ON NUMERICAL SEMIGROUPS IGNACIO GARCÍA-MARCO AND KOLJA KNAUER ABSTRACT. We consider the two-player game chomp on posets associated to numerical semigroups and show that the analysis of strategies
More informationCriteria for existence of semigroup homomorphisms and projective rank functions. George M. Bergman
Criteria for existence of semigroup homomorphisms and projective rank functions George M. Bergman Suppose A, S, and T are semigroups, e: A S and f: A T semigroup homomorphisms, and X a generating set for
More informationThe Mountaintop Guru of Mathematics
The Mountaintop Guru of Mathematics New Directions in Boij-Söderberg Theory The cone of Betti diagrams over a hypersurface ring of low embedding dimension Courtney Gibbons University of Nebraska Lincoln
More informationFILTERED RINGS AND MODULES. GRADINGS AND COMPLETIONS.
FILTERED RINGS AND MODULES. GRADINGS AND COMPLETIONS. Let A be a ring, for simplicity assumed commutative. A filtering, or filtration, of an A module M means a descending sequence of submodules M = M 0
More informationHILBERT REGULARITY OF Z-GRADED MODULES OVER POLYNOMIAL RINGS
JOURNAL OF COMMUTATIVE ALGEBRA Volume 9, Number, Summer 7 HILBERT REGULARITY OF Z-GRADED MODULES OVER POLYNOMIAL RINGS WINFRIED BRUNS, JULIO JOSÉ MOYANO-FERNÁNDEZ AND JAN ULICZKA ABSTRACT Let M be a finitely
More informationThe Hilbert functions which force the Weak Lefschetz Property
The Hilbert functions which force the Weak Lefschetz Property JUAN MIGLIORE Department of Mathematics, University of Notre Dame, Notre Dame, IN 46556, USA E-mail: Juan.C.Migliore.1@nd.edu FABRIZIO ZANELLO
More informationH A A}. ) < k, then there are constants c t such that c t α t = 0. j=1 H i j
M ath. Res. Lett. 16 (2009), no. 1, 171 182 c International Press 2009 THE ORLIK-TERAO ALGEBRA AND 2-FORMALITY Hal Schenck and Ştefan O. Tohǎneanu Abstract. The Orlik-Solomon algebra is the cohomology
More informationarxiv: v1 [math.ac] 18 Mar 2014
LINEARLY RELATED POLYOMINOES arxiv:1403.4349v1 [math.ac] 18 Mar 2014 VIVIANA ENE, JÜRGEN HERZOG, TAKAYUKI HIBI Abstract. We classify all convex polyomino ideals which are linearly related or have a linear
More informationAlgebra Homework, Edition 2 9 September 2010
Algebra Homework, Edition 2 9 September 2010 Problem 6. (1) Let I and J be ideals of a commutative ring R with I + J = R. Prove that IJ = I J. (2) Let I, J, and K be ideals of a principal ideal domain.
More informationModules, ideals and their. Rees algebras
Modules, ideals and their Rees algebras Santiago Zarzuela University of Barcelona Conference on Commutative, Combinatorial and Computational Algebra In Honour to Pilar Pisón-Casares Sevilla, February 11-16,
More informationH. Schubert, Kalkül der abzählenden Geometrie, 1879.
H. Schubert, Kalkül der abzählenden Geometrie, 879. Problem: Given mp subspaces of dimension p in general position in a vector space of dimension m + p, how many subspaces of dimension m intersect all
More informationUnit 3 Vocabulary. An algebraic expression that can contains. variables, numbers and operators (like +, An equation is a math sentence stating
Hart Interactive Math Algebra 1 MODULE 2 An algebraic expression that can contains 1 Algebraic Expression variables, numbers and operators (like +,, x and ). 1 Equation An equation is a math sentence stating
More informationMETRIC HEIGHTS ON AN ABELIAN GROUP
ROCKY MOUNTAIN JOURNAL OF MATHEMATICS Volume 44, Number 6, 2014 METRIC HEIGHTS ON AN ABELIAN GROUP CHARLES L. SAMUELS ABSTRACT. Suppose mα) denotes the Mahler measure of the non-zero algebraic number α.
More informationABSTRACT NONSINGULAR CURVES
ABSTRACT NONSINGULAR CURVES Affine Varieties Notation. Let k be a field, such as the rational numbers Q or the complex numbers C. We call affine n-space the collection A n k of points P = a 1, a,..., a
More information12x + 18y = 50. 2x + v = 12. (x, v) = (6 + k, 2k), k Z.
Math 3, Fall 010 Assignment 3 Solutions Exercise 1. Find all the integral solutions of the following linear diophantine equations. Be sure to justify your answers. (i) 3x + y = 7. (ii) 1x + 18y = 50. (iii)
More informationPolynomial Rings. i=0. i=0. n+m. i=0. k=0
Polynomial Rings 1. Definitions and Basic Properties For convenience, the ring will always be a commutative ring with identity. Basic Properties The polynomial ring R[x] in the indeterminate x with coefficients
More informationAssociated graded rings of one-dimensional analytically irreducible rings
Associated graded rings of one-dimensional analytically irreducible rings V. Barucci Dipartimento di matematica Università di Roma 1 Piazzale Aldo Moro 2 00185 Roma Italy email barucci@mat.uniroma1.it
More informationREMARKS ON REFLEXIVE MODULES, COVERS, AND ENVELOPES
REMARKS ON REFLEXIVE MODULES, COVERS, AND ENVELOPES RICHARD BELSHOFF Abstract. We present results on reflexive modules over Gorenstein rings which generalize results of Serre and Samuel on reflexive modules
More informationPARTITIONS WITH FIXED DIFFERENCES BETWEEN LARGEST AND SMALLEST PARTS
PARTITIONS WITH FIXED DIFFERENCES BETWEEN LARGEST AND SMALLEST PARTS GEORGE E. ANDREWS, MATTHIAS BECK, AND NEVILLE ROBBINS Abstract. We study the number p(n, t) of partitions of n with difference t between
More informationDepth of some square free monomial ideals
Bull. Math. Soc. Sci. Math. Roumanie Tome 56(104) No. 1, 2013, 117 124 Depth of some square free monomial ideals by Dorin Popescu and Andrei Zarojanu Dedicated to the memory of Nicolae Popescu (1937-2010)
More informationON A FAMILY OF ELLIPTIC CURVES
UNIVERSITATIS IAGELLONICAE ACTA MATHEMATICA, FASCICULUS XLIII 005 ON A FAMILY OF ELLIPTIC CURVES by Anna Antoniewicz Abstract. The main aim of this paper is to put a lower bound on the rank of elliptic
More informationVANISHING THEOREMS FOR COMPLETE INTERSECTIONS. Craig Huneke, David A. Jorgensen and Roger Wiegand. August 15, 2000
VANISHING THEOREMS FOR COMPLETE INTERSECTIONS Craig Huneke, David A. Jorgensen and Roger Wiegand August 15, 2000 The starting point for this work is Auslander s seminal paper [A]. The main focus of his
More informationBoundary of Cohen-Macaulay cone and asymptotic behavior of system of ideals
Boundary of Cohen-Macaulay cone and asymptotic behavior of system of ideals Kazuhiko Kurano Meiji University 1 Introduction On a smooth projective variety, we can define the intersection number for a given
More informationHandout - Algebra Review
Algebraic Geometry Instructor: Mohamed Omar Handout - Algebra Review Sept 9 Math 176 Today will be a thorough review of the algebra prerequisites we will need throughout this course. Get through as much
More informationarxiv:math/ v1 [math.ac] 11 May 2005
EXTENSIONS OF THE MULTIPLICITY CONJECTURE arxiv:math/0505229v [math.ac] May 2005 JUAN MIGLIORE, UWE NAGEL, AND TIM RÖMER Abstract. The Multiplicity conjecture of Herzog, Huneke, and Srinivasan states an
More informationResolution of Singularities in Algebraic Varieties
Resolution of Singularities in Algebraic Varieties Emma Whitten Summer 28 Introduction Recall that algebraic geometry is the study of objects which are or locally resemble solution sets of polynomial equations.
More informationTwo-boundary lattice paths and parking functions
Two-boundary lattice paths and parking functions Joseph PS Kung 1, Xinyu Sun 2, and Catherine Yan 3,4 1 Department of Mathematics, University of North Texas, Denton, TX 76203 2,3 Department of Mathematics
More informationSubrings and Ideals 2.1 INTRODUCTION 2.2 SUBRING
Subrings and Ideals Chapter 2 2.1 INTRODUCTION In this chapter, we discuss, subrings, sub fields. Ideals and quotient ring. We begin our study by defining a subring. If (R, +, ) is a ring and S is a non-empty
More informationLIVIA HUMMEL AND THOMAS MARLEY
THE AUSLANDER-BRIDGER FORMULA AND THE GORENSTEIN PROPERTY FOR COHERENT RINGS LIVIA HUMMEL AND THOMAS MARLEY Abstract. The concept of Gorenstein dimension, defined by Auslander and Bridger for finitely
More informationDIRAC S THEOREM ON CHORDAL GRAPHS
Seminar Series in Mathematics: Algebra 200, 1 7 DIRAC S THEOREM ON CHORDAL GRAPHS Let G be a finite graph. Definition 1. The graph G is called chordal, if each cycle of length has a chord. Theorem 2 (Dirac).
More informationPaul E. Bland and Patrick F. Smith (Received April 2002)
NEW ZEALAND JOURNAL OF MATHEMATICS Volume 32 (2003), 105 115 INJECTIVE AND PROJECTIVE MODULES RELATIVE TO A TORSION THEORY Paul E. Bland and Patrick F. Smith (Received April 2002) Abstract. Injective and
More informationIF THE SOCLE FITS. Andrew R. Kustin and Bernd Ulrich
IF THE SOCLE FITS Andrew R Kustin and Bernd Ulrich The following Lemma, although easy to prove, provides a surprisingly useful way to establish that two ideals are equal Lemma 11 Let R = i 0 R i be a noetherian
More informationON THE GRAPH ATTACHED TO TRUNCATED BIG WITT VECTORS
ON THE GRAPH ATTACHED TO TRUNCATED BIG WITT VECTORS NICHOLAS M. KATZ Warning to the reader After this paper was written, we became aware of S.D.Cohen s 1998 result [C-Graph, Theorem 1.4], which is both
More informationLecture 1. (i,j) N 2 kx i y j, and this makes k[x, y]
Lecture 1 1. Polynomial Rings, Gröbner Bases Definition 1.1. Let R be a ring, G an abelian semigroup, and R = i G R i a direct sum decomposition of abelian groups. R is graded (G-graded) if R i R j R i+j
More informationEXTERIOR AND SYMMETRIC POWERS OF MODULES FOR CYCLIC 2-GROUPS
EXTERIOR AND SYMMETRIC POWERS OF MODULES FOR CYCLIC 2-GROUPS FRANK IMSTEDT AND PETER SYMONDS Abstract. We prove a recursive formula for the exterior and symmetric powers of modules for a cyclic 2-group.
More informationToric Varieties. Madeline Brandt. April 26, 2017
Toric Varieties Madeline Brandt April 26, 2017 Last week we saw that we can define normal toric varieties from the data of a fan in a lattice. Today I will review this idea, and also explain how they can
More informationAlgebra. Modular arithmetic can be handled mathematically by introducing a congruence relation on the integers described in the above example.
Coding Theory Massoud Malek Algebra Congruence Relation The definition of a congruence depends on the type of algebraic structure under consideration Particular definitions of congruence can be made for
More informationCONSTRUCTIONS OF GORENSTEIN RINGS
CONSTRUCTIONS OF GORENSTEIN RINGS GUNTRAM HAINKE AND ALMAR KAID 1. Introduction This is a summary of the fourth tutorial handed out at the CoCoA summer school 2005. We discuss two well known methods of
More informationGeneralized Alexander duality and applications. Osaka Journal of Mathematics. 38(2) P.469-P.485
Title Generalized Alexander duality and applications Author(s) Romer, Tim Citation Osaka Journal of Mathematics. 38(2) P.469-P.485 Issue Date 2001-06 Text Version publisher URL https://doi.org/10.18910/4757
More informationPolynomial functions on subsets of non-commutative rings a link between ringsets and null-ideal sets
Polynomial functions on subsets of non-commutative rings a lin between ringsets and null-ideal sets Sophie Frisch 1, 1 Institut für Analysis und Zahlentheorie, Technische Universität Graz, Koperniusgasse
More informationMATH 326: RINGS AND MODULES STEFAN GILLE
MATH 326: RINGS AND MODULES STEFAN GILLE 1 2 STEFAN GILLE 1. Rings We recall first the definition of a group. 1.1. Definition. Let G be a non empty set. The set G is called a group if there is a map called
More information