We provide an explicit computation over the integers of the bar version
of the
monopole Floer homology of a three-manifold in terms of a new invariant associated
to its triple cup product, called extended cup homology. This refines previous
computations over fields of characteristic zero by Kronheimer and Mrowka, who
established a relationship to Atiyah and Segal’s twisted de Rham cohomology, and
characteristic two by Lidman using surgery techniques in Heegaard Floer
theory.
In order to do so, we first develop a general framework to study the homotopical
properties of the cohomology of a dga twisted with respect a particular kind of
Maurer–Cartan element called a twisting sequence. Then, for dgas equipped
with the additional structure of a Hirsch algebra (which consists of certain
higher operations that measure the failure of strict commutativity and related
associativity properties), we develop a product on twisting sequences and
a theory of rational characteristic classes. These are inspired by Kraines’
classical construction of higher Massey products and may be of independent
interest.
We then compute the most important infinite family of such higher
operations explicitly for the minimal cubical realization of the torus.
Building on the work of Kronheimer and Mrowka, the determination
of
follows from these computations and certain functoriality properties of the rational
characteristic classes.