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Guangcun Lu

Publications and source records attributed to Guangcun Lu.

At least 37 records · Page 2Linked to original sources

Representation formula for symmetric symplectic capacity and applications

This is the second installment in a series of papers aimed at generalizing symplectic capacities and homologies. We study symmetric versions of symplectic capacities for real symplectic manifolds, and obtain corresponding results for them to those of the first [19] of this series (such as representation formula, a theorem by Evgeni Neduv, Brunn-Minkowski type inequality and Minkowski billiard trajectories proposed by Artstein-Avidan-Ostrover).

math.SG↗

Parameterized splitting theorems and bifurcations for potential operators

We show that parameterized versions of splitting theorems in Morse theory can be effectively used to generalize some famous bifurcation theorems for potential operators. In particular, such generalizations based on the author's recent splitting theorems [38, 39, 42, 43] and that of [8] are given though potential operators in [42, 43] have weaker differentiability, even discontinuous. As applications, we obtain many bifurcation results for quasi-linear elliptic Euler equations and systems of higher order.

math.FA↗

Morse theory methods for a class of quasi-linear elliptic systems of higher order

We develop the local Morse theory for a class of non-twice continuously differentiable functionals on Hilbert spaces, including a new generalization of the Gromoll-Meyer's splitting theorem and a weaker Marino-Prodi perturbation type result. They are applicable to a wide range of multiple integrals with quasi-linear elliptic Euler equations and systems of higher order.

math.FA↗

On the degenerated Arnold-Givental conjecture

We present another view dealing with the Arnold-Givental conjecture on a real symplectic manifold $(M, ω, τ)$ with nonempty and compact real part $L={\rm Fix}(τ)$. For given $Λ\in (0, +\infty]$ and $m\in\N\cup\{0\}$ we show the equivalence of the following two claims: (i) $\sharp(L\capϕ^H_1(L))\ge m$ for any Hamiltonian function $H\in C_0^\infty([0, 1]\times M)$ with Hofer's norm $\|H\|<Λ$; (ii) $\sharp {\cal P}(H,τ)\ge m$ for every $H\in C^\infty_0(\R/\Z\times M)$ satisfying $H(t,x)=H(-t,τ(x))\;\forall (t,x)\in\mathbb{R}\times M$ and with Hofer's norm $\|H\|<2Λ$, where ${\cal P}(H, τ)$ is the set of all $1$-periodic solutions of $\dot{x}(t)=X_{H}(t,x(t))$ satisfying $x(-t)=τ(x(t))\;\forall t\in\R$ (which are also called brake orbits sometimes). Suppose that $(M, ω)$ is geometrical bounded for some $J\in{\cal J}(M,ω)$ with $τ^\ast J=-J$ and has a rationality index $r_ω>0$ or $r_ω=+\infty$. Using Hofer's method we prove that if the Hamiltonian $H$ in (ii) above has Hofer's norm $\|H\|<r_ω$ then $\sharp(L\capϕ^H_1(L))\ge\sharp {\cal P}_0(H,τ)\ge {\rm Cuplength}_{\F}(L)$ for $\F=\Z_2$, and further for $\F=\Z$ if $L$ is orientable, where ${\cal P}_0(H,τ)$ consists of all contractible solutions in ${\cal P}(H,τ)$.

math.SG↗

Morse theory methods for quasi-linear elliptic systems of higher order

We develop the local Morse theory for a class of non-twice continuously differentiable functionals on Hilbert spaces, including a new generalization of the Gromoll-Meyer's splitting theorem and a weaker Marino-Prodi perturbation type result. With them some critical point theorems and famous bifurcation theorems are generalized. Then we show that these are applicable to studies of quasi-linear elliptic equations and systems of higher order given by multi-dimensional variational problems as in (1.3).

math.FA↗

Existence results for coupled Dirac systems via Rabinowitz-Floer theory

In this paper, we construct the Rabinowitz-Floer homology for the coupled Dirac system \begin{equation*} \left\{ \begin{aligned} Du=\frac{\partial H}{\partial v}(x,u,v)\hspace{4mm} {\rm on} \hspace{2mm}M,\\ Dv=\frac{\partial H}{\partial u}(x,u,v)\hspace{4mm} {\rm on} \hspace{2mm}M, \end{aligned} \right. \end{equation*} where $M$ is an $n$-dimensional compact Riemannian spin manifold, $D$ is the Dirac operator on $M$, and $H:ΣM\oplus ΣM\to \mathbb{R}$ is a real valued superquadratic function of class $C^1$ with subcritical growth rates. Solutions of this system can be obtained from the critical points of a Rabinowitz-Floer functional on a product space of suitable fractional Sobolev spaces. In particular, we consider the $S^1$-equivariant $H$ that includes a nonlinearity of the form $$ H(x,u,v)=f(x)\frac{|u|^{p+1}}{p+1}+g(x)\frac{|v|^{q+1}}{q+1}, $$ where $f(x)$ and $g(x)$ are strictly positive continuous functions on $M$, and $p>1,q>1$ satisfy $$ \frac{1}{p+1}+\frac{1}{q+1}>\frac{n-1}{n}. $$ We establish the existence of a nontrivial solution by computing the Rabinowitz-Floer homology in the Morse-Bott situation.

math.AP↗

Splitting lemmas for the Finsler energy functional on the space of $H^1$-curves

We establish the splitting lemmas (or generalized Morse lemmas) for the energy functionals of Finsler metrics on the natural Hilbert manifolds of $H^1$-curves around a critical point or a critical $\R^1$ orbit of a Finsler isometry invariant closed geodesic. They are the desired generalization on Finsler manifolds of the corresponding Gromoll-Meyer's splitting lemmas on Riemannian manifolds (\cite{GM1, GM2}). As an application we extend to Finsler manifolds a result by Grove and Tanaka \cite{GroTa78, Tan82} about the existence of infinitely many, geometrically distinct, isometry invariant closed geodesics on a closed Riemannian manifold.

math.DG↗

The splitting lemmas for nonsmooth functionals on Hilbert spaces II. The case at infinity

We generalize the Bartsch-Li's splitting lemma at infinity for $C^2$-functionals in [2] and some later variants of it to a class of continuously directional differentiable functionals on Hilbert spaces. Different from the previous flow methods our proof is to combine the ideas of the Morse-Palais lemma due to Duc-Hung-Khai [9] with some techniques from [11], [17], [18]. A simple application is also presented.

math.FA↗

Methods of infinite dimensional Morse theory for geodesics on Finsler manifolds

We prove the shifting theorems of the critical groups of critical points and critical orbits for the energy functionals of Finsler metrics on Hilbert manifolds of $H^1$-curves, and two splitting lemmas for the functionals on Banach manifolds of $C^1$-curves. Two results on critical groups of iterated closed geodesics are also proved; their corresponding versions on Riemannian manifolds are based on the usual splitting lemma by Gromoll and Meyer (1969). Our approach consists in deforming the square of the Finsler metric in a Lagrangian which is smooth also on the zero section and then in using the splitting lemma for nonsmooth functionals that the author recently developed in Lu (2011, 0000, 2013). The argument does not involve finite-dimensional approximations and any Palais' result in Palais (1966). As an application, we extend to Finsler manifolds a result by V. Bangert and W. Klingenberg (1983) about the existence of infinitely many, geometrically distinct, closed geodesics on a compact Riemannian manifold.

math.DG↗

The splitting lemmas for nonsmooth functionals on Hilbert spaces I

The Gromoll-Meyer's generalized Morse lemma (so called splitting lemma) near degenerate critical points on Hilbert spaces, which is one of key results in infinite dimensional Morse theory, is usually stated for at least $C^2$-smooth functionals. It obstructs one using Morse theory to study most of variational problems of form $F(u)=\int_Ωf(x, u,..., D^mu)dx$ as in (\ref{e:1.1}). In this paper we establish a splitting theorem and a shifting theorem for a class of continuously directional differentiable functionals (lower than $C^1$) on a Hilbert space $H$ which have higher smoothness (but lower than $C^2$) on a densely and continuously imbedded Banach space $X\subset H$ near a critical point lying in $X$. (This splitting theorem generalize almost all previous ones to my knowledge). Moreover, a new theorem of Poincaré-Hopf type and a relation between critical groups of the functional on $H$ and $X$ are given. Different from the usual implicit function theorem method and dynamical system one our proof is to combine the ideas of the Morse-Palais lemma due to Duc-Hung-Khai \cite{DHK} with some techniques from \cite{JM, Skr, Va1}. Our theory is applicable to the Lagrangian systems on compact manifolds and boundary value problems for a large class of nonlinear higher order elliptic equations.

math.FA↗

The splitting lemmas for nonsmooth functionals on Hilbert spaces

The usual Gromoll-Meyer's generalized Morse lemma near degenerate critical points on Hilbert spaces, so called splitting lemma, is stated for at least $C^2$-smooth functionals. In this paper we establish a splitting theorem and a shifting theorem for a class of continuously directional differentiable functionals (lower than $C^1$) on a Hilbert space $H$ which have higher smoothness (but lower than $C^2$) on a densely and continuously imbedded Banach space $X\subset H$ near a critical point lying in $X$. (This splitting theorem generalize almost all previous ones to my knowledge). Moreover, a new theorem of Poincaré-Hopf type and a relation between critical groups of the functional on $H$ and $X$ are given. The corresponding version at critical submanifolds is presented. We also generalize the Bartsch-Li's splitting lemma at infinity in \cite{BaLi} and some variants of it to a class of continuously directional differentiable functionals on Hilbert spaces. Our proof methods are to combine the proof ideas of the Morse-Palais lemma due to Duc-Hung-Khai \cite{DHK} with some techniques from \cite{JM, Skr, Va1}. Our theory is applicable to the Lagrangian system on compact manifolds and boundary value problems for a large class of nonlinear higher order elliptic equations.

math.FA↗

Deforming symplectomorphism of certain irreducible Hermitian symmetric spaces of compact type by mean curvature flow

In this paper, we generalize Medos-Wang's arguments and results on the mean curvature flow deformations of symplectomorphisms of $\CP^n$ in \cite{MeWa} to complex Grassmann manifold $G(n, n+m;\C)$ and compact totally geodesic Kähler-Einstein submanifolds of $G(n, 2n;\C)$ such as irreducible Hermitian symmetric spaces $SO(2n)/U(n)$ and $Sp(n)/U(n)$ (in the terminology of \cite[p. 518]{He}). We also give an abstract result and discuss the case of complex tori.

math.SG↗

Corrigendum: The Conley conjecture for Hamiltonian systems on the cotangent bundle and its analogue for Lagrangian systems

In lines 8-11 of \cite[pp. 2977]{Lu} we wrote: "For integer $m\ge 3$, if $M$ is $C^m$-smooth and $C^{m-1}$-smooth $L:\R\times TM\to\R$ satisfies the assumptions (L1)-(L3), then the functional ${\cal L}_τ$ is $C^2$-smooth, bounded below, satisfies the Palais-Smale condition, and all critical points of it have finite Morse indexes and nullities (see \cite[Prop.4.1, 4.2]{AbF} and \cite{Be})." However, as proved in \cite{AbSc1} the claim that ${\cal L}_τ$ is $C^2$-smooth is true if and only if for every $(t,q)$ the function $v\mapsto L(t,q,v)$ is a polynomial of degree at most 2. So the arguments in \cite{Lu} is only valid for the physical Hamiltonian in (1.2) and corresponding Lagrangian therein. In this note we shall correct our arguments in \cite{Lu} with a new splitting lemma obtained in \cite{Lu2}.

math.SG↗

Some critical point theorems and applications

This paper is a continuation of \cite{Lu1}. In Part I, applying the new splitting theorems developed therein we generalize previous some results on computations of critical groups and some critical point theorems to weaker versions. In Part II (in progress), they are used to study multiple solutions for nonlinear higher order elliptic equations described in the introduction of \cite{Lu1}.

math.FA↗

The Conley conjecture for Hamiltonian systems on the cotangent bundle and its analogue for Lagrangian systems

In this paper, the Conley conjecture, which were recently proved by Franks and Handel \cite{FrHa} (for surfaces of positive genus), Hingston \cite{Hi} (for tori) and Ginzburg \cite{Gi} (for closed symplectically aspherical manifolds), is proved for $C^1$-Hamiltonian systems on the cotangent bundle of a $C^3$-smooth compact manifold $M$ without boundary, of a time 1-periodic $C^2$-smooth Hamiltonian $H:\R\times T^\ast M\to\R$ which is strongly convex and has quadratic growth on the fibers. Namely, we show that such a Hamiltonian system has an infinite sequence of contractible integral periodic solutions such that any one of them cannot be obtained from others by iterations. If $H$ also satisfies $H(-t,q, -p)=H(t,q, p)$ for any $(t,q, p)\in\R\times T^\ast M$, it is shown that the time-one map of the Hamiltonian system (if exists) has infinitely many periodic points siting in the zero section of $T^\ast M$. If $M$ is $C^5$-smooth and $\dim M>1$, $H$ is of $C^4$ class and independent of time $t$, then for any $τ>0$ the corresponding system has an infinite sequence of contractible periodic solutions of periods of integral multiple of $τ$ such that any one of them cannot be obtained from others by iterations or rotations. These results are obtained by proving similar results for the Lagrangian system of the Fenchel transform of $H$, $L:\R\times TM\to\R$, which is proved to be strongly convex and to have quadratic growth in the velocities yet.

math.SG↗