Atiyah-Floer conjecture
A conjecture relating the instanton Floer homology of suitable three-dimensional manifolds with the symplectic Floer homology of moduli spaces of flat connections over surfaces, and hence with the quantum cohomology of such moduli spaces. It was originally stated by M.F. Atiyah for homology -spheres in [a1]. The extension of the conjecture to the case of mapping cylinders was prompted by A. Floer and solved in this case by S. Dostoglou and D. Salamon in [a3].
Instanton Floer homology for three-dimensional manifolds was introduced by Floer in [a10]. Let be a pair consisting of a closed oriented
-dimensional manifold
and an
-bundle
. If either
is a homology
-sphere or
and the second Stiefel–Whitney class
, then the instanton Floer homology
is defined as the homology of the Morse-type complex constructed out of the Chern–Simons functional. The critical points are flat connections and the connecting orbits are anti-self-dual connections on
decaying exponentially to flat connections
when
.
The symplectic Floer homology for Lagrangian intersections was introduced by Floer in [a11]. Let be a symplectic manifold which is monotone and simply connected. Let
and
be Lagrangian submanifolds of
. Then there are Floer homology groups
. Now the critical points are the intersection points
and the connecting orbits are
-holomorphic strips
with
,
and
, where
and
is an almost-complex structure compatible with the symplectic form.
Let be a closed oriented surface of genus
and let
be the trivial
-bundle. Then the moduli space
of flat connections on
is symplectic and smooth except at the trivial connection. Now, let
be a Heegaard splitting of a homology
-sphere and consider the trivial
-bundle
on
. Then the flat connections on
which extend to
define a Lagrangian subspace
, and analogously
. Taking care of the singularity one may define
. The Atiyah–Floer conjecture reads
![]() | (a1) |
This was originally conjectured by Atiyah in [a1]. An overview of the problem appears in [a8]. The problem is still open (as of 2000).
The symplectic Floer homology for a symplectic mapping was introduced by Floer in [a12]. Let be a symplectic manifold which is monotone and simply connected. Let
be a symplectomorphism. Then the symplectic Floer homology
can be defined as the Morse-type theory where the critical points are the fixed points of
and the connecting orbits are
-holomorphic strips
with
which converge to fixed points
of
as
. For
, Floer proved [a12] that
. Moreover, there is a natural ring structure for the symplectic Floer homology [a8], and in [a7] it is proved that there is an isomorphism of rings
, where
is the quantum cohomology of
.
Let be a closed oriented surface of genus
and let
be the non-trivial
-bundle. The moduli space of flat connections
is a smooth symplectic manifold. Consider the mapping cylinder
of a diffeomorphism
. This
fibres over the circle
with fibre
. Lift
to a bundle mapping
. This gives an
-bundle
. On the other hand,
induces a mapping
. The Atiyah–Floer conjecture for mapping cylinders was proposed by Floer [a4] and reads:
![]() | (a2) |
In [a3], Dostoglou and Salamon prove the existence of an isomorphism between these two Floer homologies by constructing an isomorphism at the chain level and identifying the boundary operators. The idea is named adiabatic limit and consists of stretching in the direction orthogonal to
.
A very important case is that of . Then
and
is the
-bundle with
. Therefore,
![]() | (a3) |
![]() |
Both Floer homologies have natural product structures, introduced by S.K. Donaldson (see [a8]). A stronger version of the Atiyah–Floer conjecture establishes that (a3) is an isomorphism of rings.
The existence of such an isomorphism has been proved by V. Muñoz in [a5], [a6] by giving an explicit presentation of both rings in terms of the natural generators of the cohomology of and using the relationship of instanton Floer homology of
-manifolds with Donaldson invariants of
-manifolds [a2]. Also, in [a9] Salamon proves that the adiabatic limit isomorphism is indeed a ring isomorphism.
References
[a1] | M.F. Atiyah, "New invariants of three and four dimensional manifolds" Proc. Symp. Pure Math. , 48 (1988) |
[a2] | S.K. Donaldson, "On the work of Andreas Floer" Jahresber. Deutsch. Math. Verein. , 95 (1993) pp. 103–120 |
[a3] | S. Dostoglou, D. Salamon, "Self-dual instantons and holomorphic curves" Ann. of Math. , 139 (1994) pp. 581–640 |
[a4] | S. Dostoglou, D. Salamon, "Instanton homology and symplectic fixed points" D. Salamon (ed.) , Symplectic Geometry: Proc. Conf. , London Math. Soc. Lecture Notes , 192 , Cambridge Univ. Press (1993) pp. 57–94 |
[a5] | V. Muñoz, "Ring structure of the Floer cohomology of ![]() |
[a6] | V. Muñoz, "Quantum cohomology of the moduli space of stable bundles over a Riemann surface" Duke Math. J. , 98 (1999) pp. 525–540 |
[a7] | S. Piunikhin, D. Salamon, M. Schwarz, "Symplectic Floer–Donaldson theory and quantum cohomology" C.B. Thomas (ed.) , Contact and Symplectic Geometry , Publ. Newton Inst. , 8 , Cambridge Univ. Press (1996) pp. 171–200 |
[a8] | D. Salamon, "Lagrangian intersections, ![]() |
[a9] | D. Salamon, "Quantum products for mapping tori and the Atiyah–Floer conjecture" Preprint ETH-Zürich (1999) |
[a10] | A. Floer, "An instanton invariant for ![]() |
[a11] | A. Floer, "Symplectic fixed points and holomorphic spheres" Comm. Math. Phys. , 120 (1989) pp. 575–611 |
[a12] | A. Floer, "Morse theory for the symplectic action" J. Diff. Geom. , 28 (1988) pp. 513–547 |
Atiyah-Floer conjecture. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Atiyah-Floer_conjecture&oldid=22037