5,021 reputation
11643
bio website dm.unipi.it/~martelli
location Pisa (Italy)
age 41
visits member for 3 years, 11 months
seen 16 hours ago
Assistant professor (ricercatore) at Math Dept (University of Pisa)

Apr
11
comment On trivalent spines of surfaces
isn't it the other way round? I would think that without labelled points the situation is easier: spines are dual to ideal triangulations of the surface and Hatcher's argument applies. But maybe I am confused by these points.
Apr
8
answered On trivalent spines of surfaces
Feb
28
revised Does a small-area sphere in a 3-manifold bound a small ball?
added 13 characters in body
Feb
28
comment Does a small-area sphere in a 3-manifold bound a small ball?
thanks! The adaptation of Alexander's proof does not seem totally obvious to me: you should use that R^3 has a metric which is periodic over a group acting co-complactly, otherwise the theorem is clearly false (since R^3 is not compact).
Feb
28
awarded  Nice Question
Feb
27
comment Does a small-area sphere in a 3-manifold bound a small ball?
AFAIK, the isoperimetric inequality tells you that a null-homotopic small sphere bounds a small region, but that small region might not be a ball: the ball could be on the other side. This confuses me a bit.
Feb
27
revised Does a small-area sphere in a 3-manifold bound a small ball?
added 345 characters in body
Feb
27
asked Does a small-area sphere in a 3-manifold bound a small ball?
Feb
22
reviewed Approve suggested edit on If Gaussian measures on a Hilbert space converge weakly to 0, how do their covariance operators converge?
Feb
20
awarded  Nice Question
Feb
20
revised Fox re-imbedding theorem in dimension four
+ tag
Feb
19
revised Fox re-imbedding theorem in dimension four
added 22 characters in body
Feb
19
asked Fox re-imbedding theorem in dimension four
Feb
13
awarded  Good Question
Jan
26
awarded  Enlightened
Jan
26
awarded  Nice Answer
Jan
12
revised The history of the geometrization of closed surfaces
typos
Jan
10
reviewed Approve suggested edit on Is there a similar theorem in the partially hyperbolic case?
Jan
8
reviewed Approve suggested edit on Derivations of algebra of smooth $g$-valued function?
Jan
6
awarded  Popular Question