Stable maps of curves and algebraic equivalence of 1-cycles

We show that algebraic equivalence of images of stable maps of curves lifts to deformation equivalence of the stable maps. The main applications concern A1(X), the group of 1-cycles modulo algebraic equivalence, for smooth, separably rationally connected varieties. If K∕k is an algebraic extension, then the kernel of A1(Xk)→A1(XK) is at most Z∕2Z. If k is finite, then the image equals the subgroup of Galois invariant cycles.

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Publication Details

Journal
Duke Mathematical Journal
Published
2025-04-01
DOI
https://doi.org/10.1215/00127094-2024-0045
Primary Topic
Algebraic Geometry and Number Theory
Type
article
Field-Weighted Citation Impact
0.00
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article

Stable maps of curves and algebraic equivalence of 1-cycles

Janós Kollár, Zhiyu Tian
Duke Mathematical Journal
Algebraic Geometry and Number Theory
article

Stable maps of curves and algebraic equivalence of 1-cycles

Janós Kollár, Zhiyu Tian
article en

Abstract

We show that algebraic equivalence of images of stable maps of curves lifts to deformation equivalence of the stable maps. The main applications concern A1(X), the group of 1-cycles modulo algebraic equivalence, for smooth, separably rationally connected varieties. If K∕k is an algebraic extension, then the kernel of A1(Xk)→A1(XK) is at most Z∕2Z. If k is finite, then the image equals the subgroup of Galois invariant cycles.

Duke Mathematical JournalVol. 174(5)
Princeton University (US), Peking University (CN), Peking University International Hospital (CN)
Openalex Percentile: Top 85%
Algebraic Geometry and Number Theory
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