Explicit K-stability of Fano Varieties

This thesis completes the classification of local stability thresholds (δ-invariant) for smooth del Pezzo surfaces of degree 2 and explores the compactification of K-moduli for Fano 3-folds. In the first part, we show that this invariant is irrational if and only if there is a unique (-1)-curve pass...

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Main Author: Etxabarri Alberdi, Erroxe
Format: Thesis (University of Nottingham only)
Language:English
Published: 2024
Subjects:
Online Access:https://eprints.nottingham.ac.uk/79388/
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author Etxabarri Alberdi, Erroxe
author_facet Etxabarri Alberdi, Erroxe
author_sort Etxabarri Alberdi, Erroxe
building Nottingham Research Data Repository
collection Online Access
description This thesis completes the classification of local stability thresholds (δ-invariant) for smooth del Pezzo surfaces of degree 2 and explores the compactification of K-moduli for Fano 3-folds. In the first part, we show that this invariant is irrational if and only if there is a unique (-1)-curve passing through the point where we are computing the local invariant. This work can be useful for future verification of K-stability in higher dimensions, this is because the computations of δ-invariants of higher dimensional varieties are often reduced to the computations of δ-invariants of del Pezzo surfaces. The irrationality of the local stability threshold also implies the existence of infinitely many local degenerations of the variety, which can lead to interesting further studies. In the second part, we work on the compactification of one-dimensional components of the moduli spaces of Fano 3-folds by studying degenerate objects. The result on K-moduli gives some of the few existing examples of compactifications of components of the K-moduli space for Fano varieties. There are a total of 6 families with one-dimensional moduli. In this thesis, we focus on 3 of those families, we explain the parameterization of each family, the proof of K-polystability of singular elements and the compactification of the K-moduli component by explicitly describing each K-polystable member of the family.
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spelling nottingham-793882024-12-13T04:40:14Z https://eprints.nottingham.ac.uk/79388/ Explicit K-stability of Fano Varieties Etxabarri Alberdi, Erroxe This thesis completes the classification of local stability thresholds (δ-invariant) for smooth del Pezzo surfaces of degree 2 and explores the compactification of K-moduli for Fano 3-folds. In the first part, we show that this invariant is irrational if and only if there is a unique (-1)-curve passing through the point where we are computing the local invariant. This work can be useful for future verification of K-stability in higher dimensions, this is because the computations of δ-invariants of higher dimensional varieties are often reduced to the computations of δ-invariants of del Pezzo surfaces. The irrationality of the local stability threshold also implies the existence of infinitely many local degenerations of the variety, which can lead to interesting further studies. In the second part, we work on the compactification of one-dimensional components of the moduli spaces of Fano 3-folds by studying degenerate objects. The result on K-moduli gives some of the few existing examples of compactifications of components of the K-moduli space for Fano varieties. There are a total of 6 families with one-dimensional moduli. In this thesis, we focus on 3 of those families, we explain the parameterization of each family, the proof of K-polystability of singular elements and the compactification of the K-moduli component by explicitly describing each K-polystable member of the family. 2024-12-13 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en cc_by https://eprints.nottingham.ac.uk/79388/1/Thesis%20Final%20corrected.pdf Etxabarri Alberdi, Erroxe (2024) Explicit K-stability of Fano Varieties. PhD thesis, University of Nottingham. K-stability K-moduli Birational Geometry algebraic geometry manifolds
spellingShingle K-stability
K-moduli
Birational Geometry
algebraic geometry
manifolds
Etxabarri Alberdi, Erroxe
Explicit K-stability of Fano Varieties
title Explicit K-stability of Fano Varieties
title_full Explicit K-stability of Fano Varieties
title_fullStr Explicit K-stability of Fano Varieties
title_full_unstemmed Explicit K-stability of Fano Varieties
title_short Explicit K-stability of Fano Varieties
title_sort explicit k-stability of fano varieties
topic K-stability
K-moduli
Birational Geometry
algebraic geometry
manifolds
url https://eprints.nottingham.ac.uk/79388/