## Betti numbers and regularity of projective monomial curves

dc.contributor.author | Grieve, Nathan | |

dc.contributor.other | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) | en |

dc.date | 2008-09-24 09:49:35.462 | en |

dc.date.accessioned | 2008-09-25T12:33:21Z | |

dc.date.available | 2008-09-25T12:33:21Z | |

dc.date.issued | 2008-09-25T12:33:21Z | |

dc.identifier.uri | http://hdl.handle.net/1974/1474 | |

dc.description | Thesis (Master, Mathematics & Statistics) -- Queen's University, 2008-09-24 09:49:35.462 | en |

dc.description.abstract | In this thesis we describe how the balancing of the $\operatorname{Tor}$ functor can be used to compute the minimal free resolution of a graded module $M$ over the polynomial ring $B=\mathbb{K}[X_0,\dots,X_m]$ ($\mathbb{K}$ a field $X_i$'s indeterminates). Using a correspondence due to R. Stanley and M. Hochster, we explicitly show how this approach can be used in the case when $M=\mathbb{K}[S]$, the semigroup ring of a subsemigroup $S\subseteq \mathbb{N}^l$ (containing $0$) over $\mathbb{K}$ and when $M$ is a monomial ideal of $B$. We also study the class of affine semigroup rings for which $\mathbb{K}[S]\cong B/\mathfrak{p}$ is the homogeneous coordinate ring of a monomial curve in $\mathbb{P}^n_{\mathbb{K}}$. We use easily computable combinatorial and arithmetic properties of $S$ to define a notion which we call stabilization. We provide a direct proof showing how stabilization gives a bound on the $\mathbb{N}$-graded degree of minimal generators of $\mathfrak{p}$ and also show that it is related to the regularity of $\mathfrak{p}$. Moreover, we partition the above mentioned class into three cases and show that this partitioning is reflected in how the regularity is attained. An interesting consequence is that the regularity of $\mathfrak{p}$ can be effectively computed by elementary means. | en |

dc.format.extent | 737320 bytes | |

dc.format.mimetype | application/pdf | |

dc.language | en | en |

dc.language.iso | en | en |

dc.relation.ispartofseries | Canadian theses | en |

dc.rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. | en |

dc.subject | Commutative Algebra | en |

dc.subject | Combinatorics | en |

dc.title | Betti numbers and regularity of projective monomial curves | en |

dc.type | thesis | en |

dc.description.degree | Master | en |

dc.contributor.supervisor | Roberts, Leslie G. | en |

dc.contributor.department | Mathematics and Statistics | en |