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Apr
19
reviewed Close GMRES converges for $\left(\begin{array}{ccc}1&-1\\-10&12\end{array}\right)$
Apr
19
reviewed Close element or subset
Apr
19
reviewed Close Uniform convergence of sequence of functions on compact set
Apr
18
comment Homology Whitehead theorem for non simply connected spaces
@studiosus Oh, looks like you're right
Apr
18
reviewed Close Problem with a sequence with multiple integrals
Apr
18
reviewed Close how to solve the current problem of evaluating limits approching zero
Apr
18
comment Is there an injective continuous map $\mathbb{R}^2 \rightarrow \mathbb{R}$?
See en.wikipedia.org/wiki/Invariance_of_domain
Apr
18
revised Topological invariance of chern classes
edited tags
Apr
18
answered Topological invariance of chern classes
Apr
18
comment Homology Whitehead theorem for non simply connected spaces
@Olivier The first part (the inclusion of the meridian is a homology iso) follows from Alexander duality. The reference for the second part (codimension 2 sphere is unknotted iff its complement is homotopy equivalent to $S^1$) is, I believe, J. Levine, Unknotting spheres in codimension 2, Topology 4, 9–16 (1965)
Apr
18
answered Homology Whitehead theorem for non simply connected spaces
Apr
16
reviewed Close Coefficient question in generating functions
Apr
16
reviewed Close permutation with four fixed numbers
Apr
16
reviewed Close Gentle introduction to discrete vector field
Apr
16
reviewed Close Closed form questions
Apr
16
comment Homology Whitehead theorem for non simply connected spaces
(tangentially) related: Two CW complexes with isomorphic homotopy groups and homology, yet not homotopy equivalent
Apr
13
comment Complex number with 3 dimensions
@BenMillwood The link answers the OP's question «Why is there no complex number in 3 dimensions?» [and what it means exactly].
Apr
12
awarded  Enlightened
Apr
12
awarded  Nice Answer
Apr
12
comment Complex number with 3 dimensions
related: Why are the only division algebras over the real numbers the real numbers, the complex numbers, and the quaternions?