Newton-Okounkov bodies and Picard numbers on surfaces

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Titel: Newton-Okounkov bodies and Picard numbers on surfaces
Autoren: Julio-José Moyano-Fernández, Mathias Nickel, Joaquim Roé
Quelle: Dipòsit Digital de Documents de la UAB
Universitat Autònoma de Barcelona
Publication Status: Preprint
Verlagsinformationen: Universitat Autonoma de Barcelona, 2025.
Publikationsjahr: 2025
Schlagwörter: Mathematics - Algebraic Geometry, Algebraic surface, Newton-Okounkov body, Picard number, FOS: Mathematics, 14C20, 14E15, 14C22, 13A18, Blowup, 0101 mathematics, Mathematics - Commutative Algebra, Commutative Algebra (math.AC), 01 natural sciences, Algebraic Geometry (math.AG), Valuation
Beschreibung: We study the shapes of all Newton-Okounkov bodies $Δ_{v}(D)$ of a given big divisor $D$ on a surface $S$ with respect to all rank 2 valuations $v$ of $K(S)$. We obtain upper bounds for, and in many cases we determine exactly, the possible numbers of vertices of the bodies $Δ_{v}(D)$. The upper bounds are expressed in terms of Picard numbers and they are birationally invariant, as they do not depend on the model $\tilde{S}$ where the valuation $v$ becomes a flag valuation. We also conjecture that the set of all Newton-Okounkov bodies of a single ample divisor $D$ determines the Picard number of $S$, and prove that this is the case for Picard number 1, by an explicit characterization of surfaces of Picard number 1 in terms of Newton-Okounkov bodies.
25 pages. Revised version: the proof of Theorem 4.6 (Theorem C) has been rewritten to overcome a gap in (former) Lemma 4.4. Exposition has been improved throughout
Publikationsart: Article
Dateibeschreibung: application/pdf
Sprache: English
ISSN: 0214-1493
DOI: 10.5565/publmat6912501
DOI: 10.48550/arxiv.2101.05338
Zugangs-URL: http://arxiv.org/abs/2101.05338
https://ddd.uab.cat/record/304450
Rights: arXiv Non-Exclusive Distribution
URL: http://rightsstatements.org/vocab/InC/1.0/
Dokumentencode: edsair.doi.dedup.....a72dcfe3413beda1e9ce3f1a9a624ec0
Datenbank: OpenAIRE
Beschreibung
Abstract:We study the shapes of all Newton-Okounkov bodies $Δ_{v}(D)$ of a given big divisor $D$ on a surface $S$ with respect to all rank 2 valuations $v$ of $K(S)$. We obtain upper bounds for, and in many cases we determine exactly, the possible numbers of vertices of the bodies $Δ_{v}(D)$. The upper bounds are expressed in terms of Picard numbers and they are birationally invariant, as they do not depend on the model $\tilde{S}$ where the valuation $v$ becomes a flag valuation. We also conjecture that the set of all Newton-Okounkov bodies of a single ample divisor $D$ determines the Picard number of $S$, and prove that this is the case for Picard number 1, by an explicit characterization of surfaces of Picard number 1 in terms of Newton-Okounkov bodies.<br />25 pages. Revised version: the proof of Theorem 4.6 (Theorem C) has been rewritten to overcome a gap in (former) Lemma 4.4. Exposition has been improved throughout
ISSN:02141493
DOI:10.5565/publmat6912501