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reviewed Approve Can the work of Hardy & Ramanujan about partitions shed light on Hardy-Littlewood's k-tuple conjecture?
Apr
11
comment Projections of orbifolds
@Allen: it is true. In fact it is mentioned in Terng's paper.
Apr
8
revised Projections of orbifolds
These are not orbifolds.
Apr
8
comment Projections of orbifolds
By the way, these are not orbifolds, but generalized flag manifolds.
Apr
8
revised Projections of orbifolds
Added reference.
Apr
8
answered Projections of orbifolds
Mar
22
awarded  Nice Answer
Feb
21
awarded  Necromancer
Feb
1
awarded  Good Answer
Jan
13
comment embedding of quaternionic projective spaces
The embedding can be geometrically described as follows. Let $V$ be the real vector space of $3\times3$ Hermitian quaternionic matrices with fixed (real) trace, say $1$. Note that $\dim V=14$. $\mathbb HP^2$ embeds into $V$ by mapping each quaternionic line in $\mathbb H^3$ to the matrix representing the corresponding orthogonal projection onto it. The image of the embedding in $V$ consists of the idempotent matrices, and it is also an orbit of the action of the group $Sp(3)$ on $V$ by conjugation. The image sits in the unit sphere of $V$, so it can be stereographically projected to $R^{13}$.
Jan
8
revised Is there a formula for the Frobenius-Schur indicator of a rep of a Lie group?
Added table.
Jan
8
answered Is there a formula for the Frobenius-Schur indicator of a rep of a Lie group?
Dec
24
reviewed Approve How to solve $f(f(x)) = \cos(x)$?
Dec
24
comment Manifolds as simultaneous coset spaces
The existence a $G$-equivariant map $F:X\to Y$, namely, one such that $F(gx)=gF(x)$ for all $g\in G$, $x\in X$, is a necessary and sufficient condition.
Oct
25
reviewed Approve Computational complexity of low rank SDP
Jul
27
revised Check symplectomorphism property on infinitesimal generators
Added explanation.
Jul
27
answered Check symplectomorphism property on infinitesimal generators
Jul
22
accepted Calculation with weights of $E_6$
Jun
9
awarded  Nice Answer
May
16
awarded  Yearling