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1. CMB Online first
On $3$-manifolds with Torus- or Klein-bottle Category Two A subset $W$ of a closed manifold $M$ is $K$-contractible, where $K$
is a torus or Kleinbottle, if the inclusion $W\rightarrow M$ factors
homotopically through a map to $K$. The image of $\pi_1 (W)$ (for any
base point) is a subgroup of $\pi_1 (M)$ that is isomorphic to a
subgroup of a quotient group of $\pi_1 (K)$. Subsets of $M$ with this
latter property are called $\mathcal{G}_K$-contractible. We obtain a
list of the closed $3$-manifolds that can be covered by two open
$\mathcal{G}_K$-contractible subsets. This is applied to obtain a list
of the possible closed prime $3$-manifolds that can be covered by two
open $K$-contractible subsets.
Keywords:Lusternik--Schnirelmann category, coverings of $3$-manifolds by open $K$-contractible sets Categories:57N10, 55M30, 57M27, 57N16 |
2. CMB 1999 (vol 42 pp. 257)
Homotopy of Knots and the Alexander Polynomial Any knot in a 3-dimensional homology sphere is homotopic to a knot
with trivial Alexander polynomial.
Categories:57N10, 57M05, 57M25, 57N65 |
3. CMB 1997 (vol 40 pp. 370)
Which $3$-manifolds embed in $\Triod \times I \times I$? We classify the compact $3$-manifolds whose boundary is a union of
$2$-spheres, and which embed in $T \times I \times I$, where $T$ is a
triod and $I$ the unit interval. This class is described explicitly as
the set of punctured handlebodies. We also show that any $3$-manifold
in $T \times I \times I$ embeds in a punctured handlebody.
Categories:57N10, 57N35, 57Q35 |