The Arnold conjecture on a closed symplectic manifold $(M,\omega)$ says in the weakest version that for a non-degenerate Hamiltonian there are at least $k$ 1-periodic orbits where $k$ is the sum of the Betti numbers of $M$. It is easy to show that one can assume that $\omega$ is integral, so I do so in the following.


On wikipedia it says that the [Arnold conjecture](https://en.wikipedia.org/wiki/Arnold_conjecture) is solved in many cases using Floer homology. 


However, I was given the impression that this version of the Arnold conjecture has been solved in all cases, but are scattered around in several papers - due to several different complications.


**Question**: What is the current status of this weak Arnold conjecture precisely, and what are the refferences for these results?


Added: I know most of the details of the monotone case, so I am mostly interested in the more exotic cases.



Floer homology and status of the Arnold conjecture


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*V. I. Arnol'd, June 12, 1937 - June 3, 2010.*


The very sad news of his death is reported today [here](http://www.france-info.com/ressources-afp-2010-06-03-l-eminent-mathematicien-russe-vladimir-arnold-mort-subitement-en-450299-69-69.html).




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After Floer, the main difficulty in solving the weak Arnol'd conjecture on a compact symplectic manifold $M$ lies in defining a Floer chain complex generated by 1-periodic orbits of an arbitrary non-degenerate Hamiltonian $H: S^1\times M \to \mathbb{R}$, in such a way that the homology is independent of $H$. Once one has that, the remaining step (proving an isomorphism with Morse homology) can be done either by a computation with small autonomous Hamiltonians, or by a "PSS" isomorphism.


When $M$ is monotone, the crucial compactness theorems for solutions to Floer's equation (used to define the candidate-differential on the Floer complex, to prove that it squares to zero, and, in a variant, to prove the invariance of the theory) can be proved using index considerations. When $M$ is Calabi-Yau, compactness needs an additional idea, that holomorphic spheres generically don't hit cylinders solving Floer's equation. This is beautifully worked out in



> 
> Hofer, H.; Salamon, D. A. "Floer homology and Novikov rings." The Floer memorial volume, 
> 483--524, Progr. Math., 133, Birkhäuser, Basel, 1995; MR1362838.
> 


In general, where there may be holomorphic spheres with small negative Chern number, one has little choice but to allow "stable trajectories" consisting of broken Floer trajectories with holomorphic bubble-trees attached. Transversality is proved by introducing multi-valued perturbations to the equations, and this forces one to use rational coefficients. References:



> 
> Fukaya, Kenji; Ono, Kaoru. "Arnold conjecture and Gromov-Witten invariant". Topology 38 (1999), no. 5, 933-1048. MR1688434
> 



> 
> Liu, Gang; Tian, Gang, "Floer homology and Arnold conjecture", J. Differential Geom. 49 (1998), no. 1, 1-74. MR1642105
> 


[Edit: both these references offer proofs of the weak Arnol'd conjecture with rational coefficients.] For a detailed introduction to these "virtual transversality" methods, see



> 
> Salamon, Dietmar, "Lectures on Floer homology". MR1702944
> 


The technical complications of virtual transversality theory are notorious, and one could wish for a fully detailed textbook account.


What's left?


So far as I know, there is no proof for general manifolds that the number $h$ of 1-periodic orbits of a non-degenerate Hamiltonian is at least the sum of the mod $p$ Betti numbers. The strong Arnol'd conjecture for non-degenerate Hamiltonians, that $h$ is at least the minimum number of critical points of a Morse function, is wide open.


