Model solvmanifolds for Neilson theory
Philip R. Heath and Edward C. Keppelman
(
Click here for pdf version )
Existing examples of solvmanifolds
(quotients of connected simply connected
solvable Lie groups by uniform subgroups),
and their maps, seem to be sparse, to
say the least. Nilmanifolds
(quotients of connected simply connected
nilpotent Lie groups by uniform subgroups),
on the other hand, are known to be
homeomorphic to subgroups of unipotent matrix groups. Furthermore,
homotopy classes of self maps of nilmanifolds are also in one-to-one
correspondence with the homomorphisms of these subgroups and the
Nielsen theory (both ordinary and periodic) is the same as the basic
matrix Nielsen theory of tori.
Thus this latter class of spaces, serves as models for nilmanifolds and
their maps.
In contrast, the construction of and analysis of self maps of
solvmanifolds is far more complicated than for nilmanifolds, and
there seems to be no corresponding models for solvmanifolds.
The purpose of this talk is
to give the next best thing,
at least as far as Nielsen theory is concerned.
Accordingly, we construct a class of solvmanifolds (which we call
{\it models}) and their maps.
These models, unlike arbitrary solvmanifolds, exhibit a simple
necessary and sufficient condition for the existence of self maps.
They not only give a rich source of examples of solvmanifolds,
but also serve as paradigms for the Nielsen theory of solvmanifolds in
the sense that,
for any self map $f: S \to S$ of an arbitrary solvmanifold $S$,
there is an easily constructed (often simpler)
solvmanifold $S'$, and an often simpler self map $f'$ of
$S'$ that has the same Nielsen theory {(ordinary and periodic)} as $f$.
The talk will contain illustrative examples.
|