bio | website | cs.ox.ac.uk/people/… |
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location | Oxford, United Kingdom | |
age | 51 | |
visits | member for | 4 years, 7 months |
seen | yesterday | |
stats | profile views | 2,283 |
May 21 |
reviewed | Leave Open Are congruence subgroups of the modular group finitely presented? |
May 20 |
reviewed | Leave Open What criteria are to determine if two projective varieties are projectively equivalent? |
May 19 |
comment |
Looking for reference or proof to some facts stated on Anand Pillay's book
if your 2-dimensional closed sets have at least 3 elements then one doesn't need any group actions and infiniteness, it's just pure synthetic geometry to show that you sill get an affine or projective geometry. |
May 19 |
comment |
Cardinality of non-integer points in the translation of the Minkowski sum of convex hull.
counting integer points in $mP+nQ$ is quite famous question, related to mixed volumes. Perhaps you can use it to get $|S|$... |
May 19 |
comment |
Looking for reference or proof to some facts stated on Anand Pillay's book
you need infiniteness to avoid a sporadic example related to the Mathieu group $M_{22}$, I suppose. Well, I don't know how to deal with the case of 2-dimensional closed sets (a.k.a. lines) being of size 2, and locally being an infinite projective plane. |
May 19 |
comment |
Looking for reference or proof to some facts stated on Anand Pillay's book
2.1.11 is also a result that is very old, at least in geometric terms (I don't know what an "infinite homogeneous" means though). Does it mean that the rank is infinite? |
May 19 |
comment |
Looking for reference or proof to some facts stated on Anand Pillay's book
2.1.12 is a classical result in projective geometry, any good book should have it. e.g. see math.stackexchange.com/questions/549099/… for a list of books. |
May 19 |
reviewed | Close Is any F-stable maximal torus contained in some F-stable Borel subgroup? |
May 19 |
comment |
Is any F-stable maximal torus contained in some F-stable Borel subgroup?
I'm voting to close this question as it has been answered in the comments |
May 18 |
reviewed | Close Intrinsic definition of arc length |
May 16 |
comment |
Extreme points of convex hull of Minkowski sum
it seems you do not understand what conv(X) is. |
May 16 |
comment |
Extreme points of convex hull of Minkowski sum
you are not reading it right. |
May 16 |
comment |
Extreme points of convex hull of Minkowski sum
@Cusp : if $Q$ is a point $a$ then $P+Q$ is just $P$ shifted by the vector $a$, and the vertices of $P+Q$ are the vertices of $P$ shifted by $a$, and this is what I claim. |
May 16 |
comment |
Extreme points of convex hull of Minkowski sum
pictures speak for themselves here: en.wikipedia.org/wiki/Minkowski_addition |
May 16 |
comment |
Extreme points of convex hull of Minkowski sum
@AnthonyQuas : this is also an exercise :-) |
May 16 |
comment |
Extreme points of convex hull of Minkowski sum
$ext(P+Q)$ will be $conv(\{a_i+b_j\mid 1\leq i\leq p, 1\leq j\leq q\})$. It is an exercise. |
May 15 |
reviewed | Leave Open Splitting over infinite generated abelian subgroup? |
May 14 |
answered | Upper bound on Betti numbers of an intersection of hypersurfaces (or quadrics) |
May 14 |
reviewed | Approve Computing the centers of Apollonian Circle Packings |
May 14 |
reviewed | Approve A circle packing conjecture |