Symplectic (-2)-spheres and the symplectomorphism group of small rational 4-manifolds

Jun Li, Tian Jun Li

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Let (X, ω) be a symplectic rational surface. We study the space of tamed almost complex structures Jω using a fine decomposition via smooth rational curves and a relative version of the infinite dimensional Alexander- Pontrjagin duality. This decomposition provides new understandings of both the variation and the stability of the symplectomorphism group Symp(X, ω) when deforming ω In particular, we compute the rank of π1(Symp(X, ω)) with X(X) ≥ 7 in terms of the number Nω of (-2)-symplectic sphere classes.

Original languageEnglish (US)
Pages (from-to)561-606
Number of pages46
JournalPacific Journal of Mathematics
Volume304
Issue number2
DOIs
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 2020 Mathematical Sciences Publishers.

Keywords

  • Almost complex structure
  • Lagrangian root system
  • Rational symplectic manifold
  • Symplectomorphism group

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