J-tamed inflation via tame to compatible deformations

Fuente: arXiv
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Autores principales: Chakravarthy, Pranav, Payette, Jordan, Pinsonnault, Martin
Formato: Preprint
Publicado: 2024
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author Chakravarthy, Pranav
Payette, Jordan
Pinsonnault, Martin
author_facet Chakravarthy, Pranav
Payette, Jordan
Pinsonnault, Martin
contents We give a complete and self-contained exposition of the $J$-tame inflation lemma: Given any tame almost complex structure $J$ on a symplectic $4$-manifold $(M,ω)$, and given any compact, embedded, $J$-holomorphic submanifold $Z$, it is always possible to construct a deformation of symplectic forms $ω_t$ in classes $[ω_t]=[ω]+t\mathrm{PD}{Z}$, for $0\leq t$ less than an upper bound $0<T$ that only depends on the self-intersection $Z\cdot Z$. The original proofs of this fact make the unwarranted assumption that one can find a family of normal planes along $Z$ that is both $J$ invariant and $ω$-orthogonal to $TZ$ -- which amounts, in effect, to assuming the compatibility of $J$ and $ω$ along $Z$. We explain how the original constructions can be adapted to avoid this assumption when $Z$ has nonpositive self-intersection, and we discuss the difficulties with this line of argument in general to establish the full inflation when $Z$ has positive self-intersection. We overcome this problem by proving a `preparation lemma', which states that prior to inflation, one can isotope $ω$ within its cohomology class to a new form that still tames $J$ and which is compatible with $J$ along the submanifold $Z$. This preparation lemma can be regarded as an infinitesimal version of the "tamed-to-compatible" conjecture of S. K. Donaldson along an almost-complex submanifold $Z$.
format Preprint
id arxiv_https___arxiv_org_abs_2403_19110
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle J-tamed inflation via tame to compatible deformations
Chakravarthy, Pranav
Payette, Jordan
Pinsonnault, Martin
Symplectic Geometry
Primary 53D35, Secondary 57R17, 53C15, 57R52
We give a complete and self-contained exposition of the $J$-tame inflation lemma: Given any tame almost complex structure $J$ on a symplectic $4$-manifold $(M,ω)$, and given any compact, embedded, $J$-holomorphic submanifold $Z$, it is always possible to construct a deformation of symplectic forms $ω_t$ in classes $[ω_t]=[ω]+t\mathrm{PD}{Z}$, for $0\leq t$ less than an upper bound $0<T$ that only depends on the self-intersection $Z\cdot Z$. The original proofs of this fact make the unwarranted assumption that one can find a family of normal planes along $Z$ that is both $J$ invariant and $ω$-orthogonal to $TZ$ -- which amounts, in effect, to assuming the compatibility of $J$ and $ω$ along $Z$. We explain how the original constructions can be adapted to avoid this assumption when $Z$ has nonpositive self-intersection, and we discuss the difficulties with this line of argument in general to establish the full inflation when $Z$ has positive self-intersection. We overcome this problem by proving a `preparation lemma', which states that prior to inflation, one can isotope $ω$ within its cohomology class to a new form that still tames $J$ and which is compatible with $J$ along the submanifold $Z$. This preparation lemma can be regarded as an infinitesimal version of the "tamed-to-compatible" conjecture of S. K. Donaldson along an almost-complex submanifold $Z$.
title J-tamed inflation via tame to compatible deformations
topic Symplectic Geometry
Primary 53D35, Secondary 57R17, 53C15, 57R52
url https://arxiv.org/abs/2403.19110