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930
bio website cs.ox.ac.uk/people/…
location Oxford, United Kingdom
age 51
visits member for 4 years, 7 months
seen yesterday

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