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Shaoyun Bai

Publications and source records attributed to Shaoyun Bai.

17 recordsLinked to original sources

A proof of the Arnold-Givental conjecture

We prove the Arnold-Givental conjecture in full generality: given a closed symplectic manifold $(X, \omega)$, an anti-symplectic involution $\tau_X: X \to X$ with fixed point set $L={\rm Fix}(\tau_X)$, and a Hamiltonian diffeomorphism $\phi: X \to X$ such that $\phi(L)$ intersects transversely with $L$, the following inequality holds: \[ \# \big( \phi(L) \cap L \big) \geq {\mathrm dim}_{{\mathbb F}_2} H_*(L; {\mathbb F}_2).\] The proof combines the methods of integral Floer theory of the first and fourth authors, a reduction to Hamiltonian Floer cohomology due to Lu, and a new idea related to localization in a $\mathbb Z/2$-equivariant Floer theory tailored to the problem.

math.SG

Quantum Steenrod powers and Hamiltonian maps

We prove a series of new results in Hamiltonian dynamics on a general closed symplectic manifold $(M, \omega)$, including: 1. If $M$ admits a Hamiltonian diffeomorphism which is either a pseudo-rotation or has finite order, then $M$ is geometrically uniruled. This resolves a variant of Problem 24 in McDuff--Salamon's list, which predicts an obstruction to the existence of such special Hamiltonian diffeomorphisms in terms of genus zero numerical invariants. 2. If a Hamiltonian possesses a periodic orbit in a non-torsion homology class, then it has infinitely many simple periodic points. The same conclusion holds if the manifold is not geometrically uniruled and the diffeomorphism is minimal for rational Floer homology. These two general results complement the known cases of the Hofer--Zehnder conjecture. 3. If a Hamiltonian diffeomorphism possesses a symplectically degenerate maximum, then it has infinitely many simple periodic points. This resolves an open question which stems from the work of Ginzburg and G\"urel. We also establish new cases of the generic Conley conjecture: infinitely many periodic points for generic Hamiltonian diffeomorphisms. The proofs rely on a systematic application of the integral Hamiltonian Floer theory package developed by the first and fourth author, a K\"unneth isomorphism in equivariant Floer homology, and new quantitative analysis of quantum power maps, which is of independent interest.

math.SG

Integral Hamiltonian Floer theory: Foundations

Continuing our previous work on the integral Arnold conjecture, we establish the foundation of Hamiltonian Floer theory over integer coefficients on any compact symplectic manifold. This package produces a well-defined chain homotopy class of Floer complexes, chain-level continuation maps, the Piunikhin--Salamon--Schwarz (PSS) isomorphism, and an associative pair-of-pants product. When the Hamiltonian is the $p$-th iteration for a prime number $p$, we also establish the $\mathbb{Z}/p$-equivariant Floer theory in characteristic $p$, including the equivariant Floer complex and the $\mathbb{Z}/p$-equivariant pair-of-pants product. Moreover, we define quantum Steenrod operations for any compact symplectic manifold and compare them with the equivariant pair-of-pants products via the $\mathbb{Z}/p$-equivariant PSS map. We also obtain chain-level invariants such as spectral numbers and barcodes, and prove quantitative properties of the equivariant pair-of-pants product. The counting theory is based on Fukaya-Ono's normally polynomial perturbation scheme and its realization by the authors, termed FOP perturbations, adapted in the abstract setting of flow categories, flow multimodules, and homotopies of flow bimodules. Along the way, we construct global Kuranishi charts for the relevant moduli spaces following Abouzaid-McLean-Smith's framework and its adaptation to the Hamiltonian Floer setting due to the authors, which may be of independent interest.

math.SG

Arithmetic geometry of quantum connections on Calabi-Yau $3$-folds

Fix a prime $p > 3$. Working over $\mathbb{Z}_p$, we show that the quantum connection of any closed Calabi-Yau threefold gives rise to a Fontaine-Laffaile module when restricted to the even degree and torsion-free part of $p$-adic quantum cohomology, whose associated Frobenius endomorphism has leading order term prescribed by the $p$-adic Gamma class. After reducing mod $p$, the divided Frobenius endomorphism defines an analogue of the inverse Cartier operator on mod $p$ quantum cohomology. We establish an $A$-model analogue of a classical result due to Katz: the conjugation of the $p$-curvature of the mod $p$ quantum connection by the inverse Cartier operator is equal to the Frobenius pullback of the quantum product, the $A$-model counterpart of the Kodaira-Spencer class. Moreover, we identify the quantum Steenrod operation with the $p$-curvature of the mod $p$ quantum connection in this setting for any prime $p$. We propose several conjectures concerning how these arithmetic structures may extend to quantum connections on more general semi-positive symplectic manifolds.

math.SG

Quantum Adams operations in quasimap K-theory

We define quantum deformations of Adams operations in $K$-theory, in the framework of quasimap quantum $K$-theory. They provide $K$-theoretic analogs of the quantum Steenrod operations from equivariant symplectic Gromov--Witten theory. We verify the compatibility of these operations with the Kahler and equivariant $q$-difference module structures, provide sample computations via $\mathbb{Z}/k$-equivariant localization, and identify them with $p$-curvature operators of the Kahler $q$-difference connections as studied in Koroteev-Smirnov. We also formulate and verify a $K$-theoretic quantum Hikita conjecture at roots of unity, and propose an indirect algebro-geometric definition of quantum Steenrod operations

math.AG

P-adic Gamma classes and overconvergent Frobenius structures for quantum connections

Consider the small quantum connection on a monotone symplectic manifold, with p-adic coefficients. We conjecture that this always admits an overconvergent Frobenius structure, whose constant term is given by a characteristic class associated to Morita's p-adic Gamma function. We prove this conjecture for toric Fano varieties and Grassmannians, and also supply additional experimental evidence.

math.AG

Bordism and resolution of singularities

We adapt algorithms for resolving the singularities of complex algebraic varieties to prove that the natural map of homology theories from complex bordism to the bordism theory of complex derived orbifolds splits. In equivariant stable homotopy theory, our techniques yield a splitting of homology theories for the map from bordism to the equivariant bordism theory of a finite group $Γ$, given by assigning to a manifold its product with $Γ$. In symplectic topology, and using recent work of Abouzaid-McLean-Smith and Hirschi-Swaminathan, we conclude that one can define complex cobordism-valued Gromov-Witten invariant for arbitrary (closed) symplectic manifolds. We apply our results to constrain the topology of the space of Hamiltonian fibrations over $S^2$. The methods we develop apply to normally complex orbifolds, and will hence lead to applications in symplectic topology that rely on moduli spaces of holomorphic curves with Lagrangian boundary conditions.

math.AT

3D mirror symmetry in positive characteristic

Via the formulation of (quantum) Hikita conjecture with coefficients in a characteristic $p$ field, we explain an arithmetic aspect of the theory of 3D mirror symmetry. Namely, we propose that the action of Steenrod-type operations and Frobenius-constant quantizations intertwine under the (quantum) Hikita isomorphism for 3D mirror pairs, and verify this for the Springer resolutions and hypertoric varieties.

math.RT

A new transversality condition on orbifolds and integer-valued Gromov-Witten type invariants

Following a proposal of Fukaya-Ono and the exploration by B. Parker, we introduce a new transversality condition, the FOP transversality condition, for sections of orbifold vector bundles $\mathcal{E} \rightarrow \mathcal{U}$ when both $\mathcal{E}$ and $\mathcal{U}$ have "normal complex structures." This notion allows one to define various integral virtual cycles on moduli spaces of pseudoholomorphic curves. Two immediate applications in symplectic topology are the definition of integer-valued Gromov-Witten type invariants in all genera for general compact symplectic manifolds using the global Kuranishi chart constructed by Abouzaid-McLean-Smith and Hirschi-Swaminathan, and an alternative proof of the cohomological splitting theorem for Hamiltonian fibrations over $S^2$ with integer coefficients by Abouzaid-McLean-Smith.

math.SG

Cohomological splitting over rationally connected bases

We prove a cohomological splitting result for Hamiltonian fibrations over enumeratively rationally connected symplectic manifolds As a key application, we prove that the cohomology of a smooth, projective family over a smooth (stably) rational projective variety splits additively over any field. The main ingredients in our arguments include the theory of Fukaya-Ono-Parker (FOP) perturbations developed by the first and third author, which allows one to define integer-valued Gromov-Witten type invariants, and variants of Abouzaid-McLean-Smith's global Kuranishi charts tailored to concrete geometric problems.

math.SG

Equivariant formality in complex-oriented theories

Let $G$ be a product of unitary groups and let $(M,ω)$ be a compact symplectic manifold with Hamiltonian $G$-action. We prove an equivariant formality result for any complex-oriented cohomology theory $\mathbb{E}^*$ (in particular, integral cohomology). This generalizes the celebrated result of Atiyah-Bott-Kirwan for rational cohomology from the 1980s. The proof does not use classical ideas but instead relies on a recent cohomological splitting result of Abouzaid-McLean-Smith for Hamiltonian fibrations over $\mathbb{CP}^1.$ Moreover, we establish analogues of the "localization" and "injectivity to fixed points" theorems for certain cohomology theories studied by Hopkins-Kuhn-Ravenel. As an application of these results, we establish a Goresky-Kottwitz-MacPherson theorem with Morava $K$-theory coefficients for Hamiltonian $T$-manifolds.

math.SG

Franks' dichotomy for toric manifolds, Hofer-Zehnder conjecture, and gauged linear sigma model

We prove that for any compact toric symplectic manifold, if a Hamiltonian diffeomorphism admits more fixed points, counted homologically, than the total Betti number, then it has infinitely many simple periodic points. This provides a vast generalization of Franks' famous two or infinity dichotomy for periodic orbits of area-preserving diffeomorphisms on the two-sphere, and establishes a conjecture attributed to Hofer-Zehnder in the case of toric manifolds. The key novelty is the application of gauged linear sigma model and its bulk deformations to the study of Hamiltonian dynamics of symplectic quotients.

math.SG

Bifurcations of embedded curves and towards an extension of Taubes' Gromov invariant to Calabi-Yau 3-folds

We define an integer-valued virtual count of embedded pseudo-holomorphic curves of two times a primitive homology class and arbitrary genus in symplectic Calabi--Yau $3$-folds, which can be viewed as an extension of Taubes' Gromov invariant. The construction depends on a detailed study of bifurcations of moduli spaces of embedded pseudo-holomorphic curves which is partially motivated by Wendl's recent solution of Bryan--Pandharipande's super-rigidity conjecture.

math.SG

On the Rouquier dimension of wrapped Fukaya categories and a conjecture of Orlov

We study the Rouquier dimension of wrapped Fukaya categories of Liouville manifolds and pairs, and apply this invariant to various problems in algebraic and symplectic geometry. On the algebro-geometric side, we introduce a new method based on symplectic flexibility and mirror symmetry to bound the Rouquier dimension of derived categories of coherent sheaves on certain complex algebraic varieties and stacks. These bounds are sharp in dimension at most $3$. As a result, we resolve a well-known conjecture of Orlov for a large class of new examples, including all toric $3$-folds and certain log Calabi--Yau surfaces. On the symplectic side, we study various quantitative questions such as: (1) given a Weinstein manifold, what is the minimal number of intersection points between the skeleton and its image under a generic compactly-supported Hamiltonian diffeomorphism? (2) what is the minimal number of critical points of a Lefschetz fibration on a Liouville manifold with Weinstein fibers? We give lower bounds for these quantities which are to our knowledge the first to go beyond the basic flexible/rigid dichotomy.

math.SG

Arnold conjecture over integers

For any closed symplectic manifold, we show that the number of 1-periodic orbits of a nondegenerate Hamiltonian thereon is bounded from below by a version of total Betti number over Z of the ambient space taking account of the total Betti number over Q and torsions of all characteristic. The proof is based on constructing a Hamiltonian Floer theory over the Novikov ring with integer coefficients, which generalizes our earlier work for constructing integer-valued Gromov-Witten type invariants. In the course of the construction, we build a Hamiltonian Floer flow category with compatible smooth global Kuranishi charts. This generalizes a recent work of Abouzaid-McLean-Smith, which might be of independent interest.

math.SG

A symplectic formula of generalized Casson invariants

Suppose Y is an integer homology 3-sphere, Taubes proved that the number of irreducible critical orbits of the perturbed Chern-Simons functional on Y, counted with signs, is equal to the algebraic intersection number of two character varieties associated with Heegaard splittings when the structure group is SU(2). Taubes' result established a relationship between gauge theory and the Casson invariant. This article proves an analogous identification result for SU(n) generalized Casson invariants. As a special case, we show that the SU(3) Casson invariant of Boden-Herald can be equivalently calculated by taking an appropriate intersection number of Lagrangian submanifolds.

math.GT

Equivariant Cerf theory and perturbative $SU(n)$ Casson invariants

We develop an equivariant Cerf theory for Morse functions on finite-dimensional manifolds with group actions, and adapt the technique to the infinite-dimensional setting to study the moduli space of perturbed flat $SU(n)$-connections. As a consequence, we prove the existence of perturbative $SU(n)$ Casson invariants on integer homology spheres for all $n\ge 3$, and write down an explicit formula when $n=4$. This generalizes the previous works of Boden and Herald.

math.GT