IJMMS 32:2 (2002) 81–92
PII. S0161171202109136
http://ijmms.hindawi.com
© Hindawi Publishing Corp.
SPACES WHOSE ONLY FINITE-SHEETED COVERS
ARE THEMSELVES. PART I
MATHEW TIMM
Received 15 September 2001
This is a survey of results and open questions related to the topology of spaces that have
no nontrivial finite-sheeted covers.
2000 Mathematics Subject Classification: 57M10, 54C10, 54H25, 20E34.
1. Introduction. This paper focuses on those connected topological spaces that
have the property that all of their finite-sheeted connected covering spaces have total
space homeomorphic to the base space. Note that there are two ways that a space M
can satisfy this property: either (1) M has no nontrivial finite-sheeted covers or (2) M
has a k-fold connected cover p : X → M for some k ≥ 2, and the total space of every
connected finite-sheeted cover p : X → M is such that X is homeomorphic to M. In
this paper, we consider those spaces that satisfy the first condition, that is, those that
have no nontrivial finite-sheeted covers. In the sequel we will survey items related to
spaces satisfying the second condition. A reader with a current interest in the second
type of space can consult [34, 39].
Section 2 of this paper presents basic terminology and some elementary examples.
Section 3 presents what is known about such metric continua. Section 4 presents what
is known in the context of spaces with more structure such as low-dimensional man-
ifolds and cell complexes. The development includes: examples, means to construct
additional examples, and statements of interesting problems that, to the knowledge
of the author, are unsolved as of this date. It is of interest to note that spaces with
no nontrivial finite-sheeted covers are related to two problems of significant histori-
cal interest: the question of whether every nonseparating planar continuum has the
fixed point property and the question of whether every compact 3-manifold can be
decomposed into finitely many geometric pieces. See Scott [35].
It has been attempted to make the paper as self-contained as possible. Unfortu-
nately, omissions have no doubt occurred. For more complete treatments of the gen-
eral topology, including the topology of inverse limit spaces, consult Engelking [8]. A
good reference for the algebraic topology is Spanier [36]. The books by Hempel [16]
and Jaco [21] and the survey paper by Scott [35] are good references on 3-manifold
topology. For the more specialized group theory, refer to the books by Robinson [33]
and Magnus et al. [27] while the more elementary group theory can be found in Hunger-
ford [20]. Also refer to Kirby [25] for the most recent version of his problem list. Kirby’s
paper, (which contains an extensive bibliography) can also be thought of as a crash
course in the topology of low-dimensional manifolds.