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Apr
18
revised the root lattice, reflections, and a coxeter element
remove greetings and signature, to make it conform to standard postings
Apr
17
comment Dao's theorem on six circumcenters associated with a cyclic hexagon
@OaiThanhĐào : one never says "I thank to you..."; it's just "Thank you...".
Apr
15
awarded  gr.group-theory
Apr
14
answered Transitive permutation groups which all of their proper subgroups are intransitive
Apr
14
revised Expressing $SO_8$ element as product of $L_u$ and $R_u$ for unit octonions $u$
TeX typo fixed
Apr
12
comment Torsion-free, normal subgroups of certain Coxeter groups
it depends; if I recall correctly, $\sqrt{2}$ appears when you work with crystallographic groups. You will find all the details in the book I cited, or in one of their papers. Here is another work of this kind : sciencedirect.com/science/article/pii/S019688580400003X
Apr
12
revised Torsion-free, normal subgroups of certain Coxeter groups
added 163 characters in body
Apr
12
reviewed Approve Gramian of a permutation group orbit
Apr
12
answered Torsion-free, normal subgroups of certain Coxeter groups
Apr
12
comment Gramian of a permutation group orbit
think of the case $k=1$. Surely $W$ need not have any symmetry in it at all.
Apr
12
comment Chasing a 1950s thesis from the University of Dhaka on block designs
looks like a typo in the title; it should be "...DesignS".
Apr
12
revised A generalization of scrolls
typo
Apr
10
reviewed Approve fourier-analysis tag wiki excerpt
Apr
5
comment If the two smallest eigenvalues of the Laplacian matrix of a network are equal to zero, then does it mean that the network is not connected?
the multiplicity of the 0 eigenvalue is the number of connected components.
Apr
5
comment Cayley graphs of $A_n.$
Benjamin's answer does prove it.
Apr
5
awarded  Nice Answer
Apr
3
revised Cayley graphs of $A_n.$
added 145 characters in body
Apr
3
answered Cayley graphs of $A_n.$
Mar
31
comment Positive definite - Inverse of sparse symmetric matrix
do you need $P^{-1}$ to be sparse? Otherwise it is trivial...
Mar
28
comment How I can prove the equality $P^{P_{\operatorname{space}}}=NP^{P_{\operatorname{space}}}=P_{\operatorname{space}}^{P_{\operatorname{space}}}$
I am not saying that complexity theory questions have no place here, I am saying that this particular one is way too technical to be of interest here.