A while ago I asked a question about recoqnizing CW complexes and got an extremely nice and concrete answer. However, I am still interested in a more general treatment of this and therefore pose the following closely related question:
Assume that XX is an n−1n−1 dimensional finite CW complex. and assume that X′ is given as a a set by the disjoint union of X and a single open cell e of dimension n. I.e. e is an open subspace of X′ homeomorphic to the open n disc (and of course X is homeomorphic to the complement). Also assume that X′ is compact Hausdorff.
Question: Are there some natural topological conditions to further put on X′ such that it follows that X′ is in fact a CW-complex with X as a sub-CW complex and e a single new cell?
Remark: The fact that X is such is equivalent to whether or not one can modify the homeomorphism of e to the open unit disc such that the inverse extends to the closed unit disc.
Ideas on answers (but I have no proofs or counter examples in any of the cases):
1) X′ is locally contractible.
2) X′ has the homotopy type of a CW complex.
3) The Combination of 1) and 2).
4) X′ is homeomorphic to a CW complex
The last is weird, but it is not clear to me that even this is enough!
Any ideas, counter examples, or references?
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