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5 votes
2 answers
222 views

$\mathbb{CP}(2)$ from gluing boundary of 4-ball

Many manifolds can be obtained from gluing the boundary of a ball. For example, $\mathbb{RP}(2)$ is obtained from gluing the two edges of a bi-gon (2-ball). Or, lens spaces are obtained from a 3-cell ...
Andi Bauer's user avatar
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4 votes
0 answers
162 views

(Non-)Orientability of non-triangulable manifolds

We heard and learned from Mike Miller's answer to Not all manifolds can be triangulated: In which dimensions? that "All orientable 5-dimensional manifolds are triangulable. In dimensions at least ...
annie marie cœur's user avatar