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seen Jul 30 at 9:43

May
4
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Jul
11
awarded  Yearling
Jul
11
awarded  Nice Question
Jun
14
comment orthogonal eigenvectors
My understanding based on en.wikipedia.org/wiki/Principal_component_analysis is that a singular value decomposition (SVD) of $X$ results in three matrices, where the first of them is composed of the eigenvectors of $X^T X$, and is used for PCA. This matrix is always orthogonal.
May
13
awarded  Caucus
Jan
7
comment Prove a graph with $2n-2$ edges has two cycles of equal length
It might be worth adding that for non connected graph, this proof still holds as there is a connected component with $k$ vertices and $2k-2$ edges, because the ratio edges/vertices of the entire graph is $2n-2/n$ so if we have a connectivity component below this ratio, there must be another above it.
Dec
9
accepted Is coNP closed under Kleene star?
Nov
28
awarded  Scholar
Nov
28
accepted Prove a graph with $2n-2$ edges has two cycles of equal length
Nov
28
awarded  Editor
Nov
28
revised Prove a graph with $2n-2$ edges has two cycles of equal length
edited body
Nov
28
asked Prove a graph with $2n-2$ edges has two cycles of equal length
Nov
16
asked Is coNP closed under Kleene star?
Mar
3
awarded  Supporter
Feb
27
comment Is quantum logic producing interesting/different mathematics?
@Qiaochu I was under the impression that if you change the laws of logic, a lot of proofs become invalid, and that makes different mathematics. @Jim From the little I know, quantum logic talks about prepositions that neither have true nor false value, which reminds me of the intuitionist approach.
Feb
26
awarded  Student
Feb
26
asked Is quantum logic producing interesting/different mathematics?