Math Stuff  Kevin Walker
I can be reached at
I work at Microsoft Station Q.
New TQFT notes: TQFTs [version 1h, 11 May 2006].
This is an early, incomplete draft.
There are notational (and other) inconsistencies, and some parts have not
been proofread.
Still, it's probably better than nothing.
1991 TQFT notes: "On Witten's 3manifold Invariants".
Other papers etc.:

Higher categories, colimits, and the blob complex
(with Scott Morrison);
a more concise, less detailed version of the longer blob paper;
to appear in Proceedings of the National Academy of Sciences,
draft version available here

The Blob Complex
(with Scott Morrison)
math.AT/1009.5025,
but this version (13 Dec 2011) might be more up to date

Projective Ribbon Permutation Statistics: a Remnant of nonAbelian Braiding in Higher Dimensions
(with Michael Freedman, Matthew B. Hastings, Chetan Nayak, XiaoLiang Qi, Zhenghan Wang)
physics.meshall/1005.0583
or Phys. Rev. B 83, 115132 (2011)

Man and machine thinking about the smooth 4dimensional Poincaré conjecture
(with Michael Freedman, Robert Gompf and Scott Morrison)
math.GT/0906.5177
or Quantum Topology Vol. 1 Issue 2 (2010) 171208

An orthogonal approach to the subfactor of a planar algebra
(with Vaughan Jones and Dimitri Shlyakhtenko),
math.OA/0807.4146
or
Pacific Journal of Mathematics Vol. 246 (2010), No. 1, 187197

On Picture (2+1)TQFTs
(with Michael Freedman, Chetan Nayak and Zhenghan Wang),
math.QA/0806.1926
or
Proceedings of the Nankai International Conference in Memory of XiaoSong Lin
(Nankai Tracts in Mathematics, Vol. 12)

Positivity of the universal pairing in 3 dimensions
(with Danny Calegari and Michael Freedman),
math.GT/0802.3208
or
Jour. Amer. Math. Soc. 23 (2010), no. 1, 107188

Fixing the functoriality of Khovanov homology
(with David Clark and Scott Morrison),
math.GT/0701339
or
Geometry & Topology 13 (2009) 14991582

Noncommuting Flux Sectors in a Tabletop Experiment
(with Alexei Kitaev and Gregory W. Moore),
hepth/0706.3410

From String Nets to Nonabelions
(with Lukasz Fidkowski, Michael Freedman, Chetan Nayak and Zhenghan Wang),
condmat/0610583
or
Commun. Math. Phys. 287, 805827 (2009)

Tilted Interferometry Realizes Universal Quantum Computation in the
Ising TQFT without Overpasses
(with Michael Freedman and Chetan Nayak),
condmat/0512072

Towards Universal Topological Quantum Computation in the ν=5/2
Fractional Quantum Hall State
(with Michael Freedman and Chetan Nayak),
condmat/0512066
or
Phys. Rev. B 73, 245307 (2006)

Universal Manifold Pairings and Positivity
(with Michael Freedman, Alexei Kitaev, Chetan Nayak, Johannes K. Slingerland and Zhenghan Wang),
math.GT/0503054
or
Geometry and Topology 9 (2005) 23032317

A Class of P,TInvariant Topological Phases of Interacting Electrons
(with Michael Freedman, Chetan Nayak, Kirill Shtengel and Zhenghan Wang),
condmat/0307511
or
Annals of Physics 310 (2004) 428492

Quantum SU(2) faithfully detects mapping class groups modulo center
(with Michael Freedman and Zhenghan Wang),
math.GT/0209150
or
Geometry and Topology 6 (2002) 523539

An Extension of Casson's Invariant,
Princeton University Press, 1992, ISBN 0691025320,
Amazon
or
P.U.P.
(One of these days I'll make a PDF version available here.
In the meantime, someone donated this DjVu version.)

An extension of Casson's invariant to rational homology spheres,
Bull. Amer. Math. Soc. 22 (1990), 261267

Configuration Spaces of Linkages, undergraduate thesis, Princeton University, 1985,
scanned PDF version
I don't necessarily recommend it, but you can also try to decipher my
slides from talks.