bio  website  madore.org/~david 

location  Paris, France  
age  37  
visits  member for  2 years, 11 months 
seen  8 hours ago  
stats  profile views  671 
2d

comment 
Flag manifolds (=Rspaces): quotients by parabolic subgroups vs. isotropy representation
I should add as a comment to this fairly old answer that the book Parabolic Geometries by Čap and Slovák, despite a slightly intimidating title, is excellent as an introduction to real and complex Lie groups and homogeneous spaces in general, and to answer my question in particular. (Arvanitoyeorgos's book is quite good, but only deals with the complex case of parabolic quotients.) 
Jul 20 
comment 
Can we define an “empirically generic” real number?
My initial formulation of the question was very unclear, I'm sorry about that, I hope I've made it better. No explicit real number can be generic, but we can hope for one to be "empirically genericlooking, in the same way that $e$ and $\pi$ are empirically randomlooking (even though they are, of course, not at all random)". 
Jul 19 
comment 
Can we define an “empirically generic” real number?
I'm sorry my original formulation of the question was very messy and unclear. I tried reformulating it (starting from "edit/clarification") in a manner that I hope is clearer and less sweeping. 
Jul 19 
revised 
Can we define an “empirically generic” real number?
try to clarify the question and make it less informal by offering different formulation 
Jul 18 
asked  Can we define an “empirically generic” real number? 
Jul 10 
revised 
Power series defined by Witt vectors / Teichmüller representatives of padics
Fix typo pointed out in comment 
Jul 10 
comment 
Power series defined by Witt vectors / Teichmüller representatives of padics
@Lubin: You're right. I replaced $\times$ by $\cdot$ everywhere. 
Jul 10 
revised 
Power series defined by Witt vectors / Teichmüller representatives of padics
replaced $\times$ by $\cdot$ for readability as per comment 
Jul 10 
revised 
Power series defined by Witt vectors / Teichmüller representatives of padics
added 573 characters in body 
Jul 10 
asked  Power series defined by Witt vectors / Teichmüller representatives of padics 
Jul 2 
awarded  Curious 
Jun 23 
awarded  Necromancer 
Jun 22 
answered  The difference between the Recursive and the Effective topos. 
May 23 
awarded  Nice Question 
May 22 
comment 
Real Lie groups versus real linear algebraic groups: differences in connexity and fundamental group
@YvesCornulier: Where can I find that statement (that the real points of a semisimple s.c. group are connected) written down and proven? That's exactly the sort of things I was wondering about, and what I was getting confused upon (e.g., the indefinite Spin groups: it doesn't help that no two authors can agree on how they are defined, let alone how connected they are); so this really explains a lot. 
May 22 
revised 
Real Lie groups versus real linear algebraic groups: differences in connexity and fundamental group
forgot to assume n is even (for there to be a difference between PGL, PSL and SL) 
May 22 
asked  Real Lie groups versus real linear algebraic groups: differences in connexity and fundamental group 
Apr 15 
awarded  Popular Question 
Apr 12 
comment 
Non split extension isomorphic (as a group) to a split extension
I did some experimental testing with Gap, and (barring errors in my code) I've ruled out the existence of examples with the order of $E$ being, or, of course, dividing, one of: 128, 192, 288, 160, 240, 360, 400 or 336. 
Apr 11 
comment 
Non split extension isomorphic (as a group) to a split extension
@YvesCornulier: Where did Joseph prove this? 