Mar
19
asked About the upper bound on the roots of the matching polynomial
Mar
18
awarded Popular Question
Mar
15
comment Is there a method to simultaneously block-diagonalize a set of group matrices?
May be one has to go to the center and do this repearedly on each block to get the full reduction.
Mar
15
comment Is there a method to simultaneously block-diagonalize a set of group matrices?
In a given example if I find a similarity transformation which diagonalizes the center then that applied on everyone else doesn't produce the same block-diagonal structure. In an irreducible representation decomposition all the matrices should have the same block structure.
Mar
5
awarded Popular Question
Feb
11
comment Is this graph and its spectrum understood?
^in the above link it says that the two vertices are adjacent iff the two vertices are at a distance $2$ in the original graph. But in the post the two vertices can be at distance one too.
Feb
11
comment Is this graph and its spectrum understood?
Are you sure this is the same thing? The definition here doesn't seem to match, mathworld.wolfram.com/HalvedCubeGraph.html
Jan
28
awarded Yearling
Jan
28
awarded Yearling
Jan
21
awarded Supporter
Jan
21
comment Why don't WolframAlpha's and Sage's answers match?
Thanks! I didn't know this technique getting decimal representations to check!
Jan
21
asked Why don't WolframAlpha's and Sage's answers match?
Jan
21
awarded Informed
Dec
10
awarded Popular Question
Nov
26
comment Busy beaver function vs low Turing degrees
Can you give the largest context or the subject in which one studies this? Do you have atextbook/review/lecture-note reference for this?
Nov
25
comment Is there an improvement for the Schur-Horn inequalities for positive semi-definite matrices?
@AllenKnutson Yes :P But this is not a trivial statement - right? The inequality for $A_{ii}$ that I wrote above comes because of the Schur-Horn inequality - right?
Nov
25
comment Is there an improvement for the Schur-Horn inequalities for positive semi-definite matrices?
@AllenKnutson About my second comment - what I mean is this - if $A$ is any Hermitian matrix then can I always say that $ (min-eigenvalue) \leq A_{ii} \leq (max-eigenvalue)$ ? (for any choice of basis) ?
Nov
25
comment Is there an improvement for the Schur-Horn inequalities for positive semi-definite matrices?
@AllenKnutson In the Schur-Horn inequalities can the diagonal entries be defined in any basis? (..because I am a bit confused by the statement here in equation 9 - terrytao.wordpress.com/2010/01/12/… - where Terence Tao seems to want to choose the "standard basis"..)
Nov
25
comment Is there an improvement for the Schur-Horn inequalities for positive semi-definite matrices?
@AllenKnutson I am not getting you - are you saying that any semi-definite matrix is also Hermitian and decomposable in some particular way such that the Schur-Horn can be used on the parts individually? Can you kindly elaborate?
Nov
23
comment Largest and smallest eigenvalues of a hermitian matrix
May be you can also help at this related question, mathoverflow.net/questions/187850/…
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