**Boston College Meeting**

Saturday,
April 14, 9:00AM-12:15PM

Math
Department, Maloney Hall, Room 560

**Speakers:**

**9:30-10:15:** Katie Mann (Brown)

**Title:** Groups acting on the circle

**Abstract: **This talk will introduce you to the
study of groups acting on the circle, and the moduli
spaces of such actions. I’ll discuss the role of
these "moduli spaces" in my research and in other
areas of geometric topology, and survey some
techniques, results, and open problems.

**10:30-11:15:**
Zhouli Xu (MIT)

**Title:** Smooth structures, stable
homotopy groups of spheres and motivic
homotopy theory

**Abstract:** Following
Kervaire-Milnor, Browder and
Hill-Hopkins-Ravenel, Guozhen Wang and I
showed that the 61-sphere has a unique
smooth structure and is the last odd
dimensional case: S^1, S^3, S^5 and S^61
are the only odd dimensional spheres with
a unique smooth structure. The proof is a
computation of stable homotopy groups of
spheres. We introduce a method that
computes differentials in the Adams
spectral sequence by comparing with
differentials in the Atiyah-Hirzebruch
spectral sequence for real projective
spectra through Kahn-Priddy theorem. I
will also discuss recent progress of
computing stable stems using motivic
homotopy theory with Dan Isaksen and
Guozhen Wang.

**11:30-12:15:** Siddhi
Krishna (BC)

**Title:** Taut Foliations, Positive 3-Braids, and
the L-Space Conjecture

**Abstract: **The L-Space Conjecture is taking the
low-dimensional topology community by storm. It aims
to relate seemingly distinct Floer homological,
algebraic, and geometric properties of a closed
3-manifold M. In particular, it predicts a 3-manifold
Y isn't "simple" from the perspective of
Heegaard-Floer homology if and only if Y admits a taut
foliation. The reverse implication was proved by
Ozsvath and Szabo. In this talk, we'll present a new
theorem supporting the forward implication. Namely,
we'll discuss how to build taut foliations for
manifolds obtained by surgery on positive 3-braid
closures. No background in Heegaard-Floer or foliation
theories will be assumed.

**Location
& Parking:**
The Math Department is located
on the fifth floor of Maloney Hall (shown on some
campus maps as 21 Campanella Way), near the center of
the main campus (shown in red on the map below). It is
adjacent to the Commonwealth Garage. See this
for more directions (including Public Transportation
information) for getting to campus.

Visitor parking is available in the Commonwealth
Garage or the Beacon Street Garage.