Prime decomposition theorem in high dimensions
[edit] 1 Problem
Every closed topological oriented manifold
has a prime decomposition

where the
are prime manifolds.
Recall that a manifold is prime if for any decomposition as a connected
sum
one of the summands
or
is homeomorphic to
.
For
-manifolds, it was shown in [Milnor1962a] that the decomposition is unique.
For high-dimensional manifolds, there is no notion of prime decomposition of smooth manifolds, but there is a notion of prime decomposition for topological manifolds.
Nevertheless, the decomposition is not unique.
In [Kreck&Lück&Teichner1994] it is proven that a
-dimensional stable version of Kneser's conjecture on the splitting of three-manifolds as connected sums. The result clearly doesn't work non-stably in dimension
and this paper gives some counterexamples. Another counterexample to the uniqueness of the decomposition is as follows.
Example 1.1.
has a homotopy equivalent twin
. The following decompositions provide a counterexample to uniqueness.

Question: Show that given any
there exist closed topological
-manifolds with non-unique prime decomposition.
Question: Give simply connected examples and give aspherical manifolds.
This question was posed by Stefan Friedl at the MATRIX meeting on Interactions between high and low dimensional topology.
[edit] 2 References
- [Kreck&Lück&Teichner1994] M. Kreck, W. Lück and P. Teichner, Stable prime decompositions of four-manifolds, Prospects in topology, Princeton Univ. Press, Princeton, NJ (1995), 251–269. MR1368662 Zbl 0928.57019
- [Milnor1962a] J. Milnor, A unique decomposition theorem for
-manifolds, Amer. J. Math. 84 (1962), 1–7. MR0142125 Zbl 0108.36501