Curriculum Vitæ: Lenhard Ng
As of September 2013. For contact information, please click here.
Research interests
Low dimensional topology, symplectic and
contact geometry, differential geometry, mathematical
physics. Particular interests: holomorphic curves, symplectic field
theory, knot theory.
Current position
Associate Professor, Mathematics Department,
Duke University, 2011present (Assistant Professor,
20062011).
Education
Past employment and positions
 Research Member, Mathematical Sciences Research Institute, spring 2010.
 Visiting Assistant Professor, Princeton University, spring 2007.
 American Institute of
Mathematics FiveYear Fellow (postdoctoral), 20012006.
 Lecturer in Mathematics and Visiting Scholar,
Stanford
University, 20022006.
 Member, Institute for
Advanced Study, 20012002, for program “Symplectic Geometry
and Holomorphic Curves”.
Selected awards, grants, and honors
 National Science Foundation: NSF CAREER grant DMS0846346 “Symplectic Field Theory and LowDimensional Topology”, 20092014; Principal Investigator, research grant DMS0706777 “Holomorphic Curves and LowDimensional Topology”, 20072010.
 American Institute of Mathematics: FiveYear Fellowship (one
fellow named per year), 20012006.
 Department of Defense: National Defense Science and Engineering
Graduate (NDSEG) fellow, 19961999.
 Fannie and John Hertz Foundation: selected as fellow, 1996.
 MIT Department of Mathematics: selected for Norman Levinson
Fellowship, 1996.
 AMS/MAA/SIAM Frank and Brennie Morgan Prize for undergraduate
research in mathematics: honorable mention (second place), 1996.
 William Lowell Putnam mathematical competition: Putnam Fellow,
1993, 1994, 1995.
 International Mathematical Olympiad: gold medal, 1992 (Moscow),
1993 (Istanbul); silver medal, 1991 (Sigtuna, Sweden).
 USA Mathematical Olympiad: first place, 1992; winner, 1991,
1993.
 Westinghouse Science Talent Search: third place, 1993.
Publications
(for links, see here)

Legendrian contact homology in the boundary of a subcritical Weinstein
4manifold (with T. Ekholm), preprint, 2013, arXiv:1307.8436.

Topological strings, Dmodel, and knot contact homology (with
M. Aganagic, T. Ekholm, and C. Vafa), preprint, 2013, arXiv:1304.5778.

On transverse invariants from Khovanov homology (with R. Lipshitz and
S. Sarkar), preprint, 2013, arXiv:1303.6371.

A topological introduction to knot contact homology, preprint, 2012,
arXiv:1210.4803.

Satellites of Legendrian knots and representations of the
ChekanovEliashberg algebra (with
D. Rutherford), Algebr. Geom. Topol. 13 (2013), no. 5, 30473097.

Knot contact homology (with T.
Ekholm, J. Etnyre, and M. Sullivan), Geom. Topol. 17
(2013), 9751112.

An atlas of Legendrian knots (with
W. Chongchitmate), Exp. Math. 22
(2013), no. 1, 2637.

Combinatorial knot contact homology and transverse
knots, Adv. Math. 227 (2011), no. 6,
21892219.

Filtrations on the knot contact homology of transverse knots (with T.
Ekholm, J. Etnyre, and M. Sullivan), Math. Annalen 355 (2013), no. 4, 15611591.

Legendrian and transverse twist knots (with J. Etnyre and V.
Vértesi), J. Eur. Math. Soc. (JEMS) 15 (2013),
no. 3, 451512.

Grid diagrams, braids, and contact geometry (with D. Thurston), Proceedings of Gökova GeometryTopology Conference 2008, 120136 (Gökova GeometryTopology Conference (GGT), Gökova, 2009).

Rational Symplectic Field Theory for Legendrian knots, Invent.
Math. 182 (2010), no. 3, 451512.

A family of transversely nonsimple knots (with T. Khandhawit),
Algebr. Geom. Topol. 10 (2010), no. 1, 293314.

A skein approach to Bennequin type
inequalities, Int. Math.
Res. Not. 2008, Art. ID rnn116, 18 pp.

Transverse knots distinguished by knot Floer homology (with P.
Ozsváth and D. Thurston), J. Symplectic Geom. 6
(2008), no. 4, 461490.

On arc index and maximal ThurstonBennequin number, J. Knot Theory
Ramifications 21 (2012), no. 4, 1250031, 11 pp.
 A Legendrian ThurstonBennequin bound from Khovanov homology,
Algebr. Geom. Topol. 5 (2005), 16371653.
 The correspondence between augmentations and rulings for
Legendrian knots (with J. Sabloff), Pacific J. Math. 224 (2006), no. 1, 141150.
 Plane curves and contact geometry, Proceedings of Gökova GeometryTopology Conference 2005, 162171 (Gökova GeometryTopology Conference (GGT), Gökova, 2006).
 Conormal bundles, contact homology, and knot invariants, in The interaction of finite type and GromovWitten invariants
at the Banff International Research Station (2003), Geom. Topol. Monogr. 8 (2006), 3348.
 Framed knot contact homology, Duke Math. J. 141
(2008), no. 2, 365406.
 Legendrian solidtorus links (with L. Traynor), J. Symplectic
Geom. 2 (2005), no. 3, 411443.
 Knot and braid invariants from contact homology II, Geom.
Topol. 9 (2005), 16031637.
 Knot and braid invariants from contact homology I, Geom.
Topol. 9 (2005), 247297.
 Problems in low dimensional contact geometry (with J. Etnyre),
in Topology and Geometry of Manifolds, Proc. Sympos. Pure
Math. 71 (2003), 337357.
 Invariants of Legendrian links and coherent orientations (with
J. Etnyre and J. Sabloff), J. Symplectic Geom. 1
(2002), no. 2, 321367.
 Computable Legendrian invariants, Topology 42
(2003), no. 1, 5582.
 Maximal ThurstonBennequin number of twobridge links,
Algebr. Geom. Topol. 1 (2001), 427434.
 The rook on the halfchessboard, or how not to diagonalize a
matrix (with K. Kedlaya), Amer. Math. Monthly 105
(1998), no. 9, 819824.
 Hamiltonian decomposition of lexicographic products of digraphs,
J. Combin. Theory Ser. B 73 (1998), no. 2, 119129.
 Hamiltonian decomposition of complete regular multipartite
digraphs, Discrete Math. 177 (1997), no. 13,
279285.
 kordered hamiltonian graphs (with M. Schultz), J.
Graph Theory 24 (1997), no. 1, 4557.
Selected invited talks
Lecture series, minicourses, and colloquia

Colloquium, University of California at Santa Barbara, November 2013.

Colloquium, Australian National University, June 2013.

Colloquium, University of Southern California, October 2012.

Invited Address “From holomorphic curves to knot invariants via the
cotangent bundle”, American
Mathematical Society Southeastern Section Meeting, Tulane University,
October 2012.

Minicourse “Knot contact homology and applications”, Contact and
Symplectic Topology Summer School and Conference,
Alfréd Rényi Institute of Mathematics,
Budapest, July 2012.

Minicourse “Knots and the topology of threemanifolds”,
conference
“O Gosto
pela Matematica”, Fundaçao
Calouste Gulbenkian, Lisbon, July 2010.

Minicourse “Legendrian knots”, Introductory
Workshop: Homology Theories of Knots and
Links, Mathematical Sciences Research Institute, January 2010.

Minicourse “Contact geometry and threedimensional
topology”, Summer
Graduate Workshop: Symplectic and Contact Geometry and
Topology, Mathematical Sciences Research Institute, August
2009.

Minicourse “Legendrian Symplectic Field Theory”, Holomorphic
Curves: Algebraic Structures and Geometric
Application, Stanford University, August 2008.

Colloquium, Dartmouth College, May 2008.

Colloquium, University of North Carolina at Chapel Hill, November 2006.
 Salomon Bochner Lectures in Mathematics, Rice University, October 2006.
 Minicourse “Invariants of knots and links via
SFT”, Workshop on
Symplectic Field Theory, Universität Leipzig, August 2006.
 Colloquium, University of California at Berkeley, February 2006.
 Colloquium, University of Illinois at UrbanaChampaign, January
2006.
 Colloquium, University of Illinois at Chicago, January 2006.
 Colloquium, Rutgers University, January 2006.
 Colloquium, University of Toronto, January 2006.
 Colloquium, University of Wisconsin, November 2005.
 Colloquium, Columbia University, September 2005.
 Minicourse, Courbes Holomorphes et Topologie de Contact, summer
school sponsored by CNRS, Berder, France, June 2003.
Conference talks

Special session on contact and symplectic topology, AMS Eastern
Sectional Meeting, Temple University, October 2013.

Lowdimensional topology after Floer, Université de Montréal, July 2013.

Low dimensional topology, Simons Center for Geometry and Physics,
Stony Brook, May 2013.

Southern California Topology Colloquium, Caltech, March 2013.

Interactions of gauge theory with contact and symplectic geometry in
dimensions 3 and 4, Banff International Research Station, March 2013.

Graduate Workshop on
Symplectic and Contact Topology (2 talks), Simons Center for Geometry
and Physics, Stony Brook,
October 2012.

Conference
on Holomorphic Curves and Low Dimensional Topology, Stanford
University, August 2012.

Tech
Topology Conference, Georgia Institute of Technology, December 2011.

Special
session on lowdimensional topology and geometry, AMS
Southeastern Section Meeting, Wake Forest University, September 2011.

Conference
on contact and symplectic topology, Université de Nantes,
June 2011.

Interactions
between contact & symplectic topology and gauge theory in
dimensions 3 and 4, Banff International Research Station, March 2011.

Special session on
topology and symplectic geometry, AMS Western Section Meeting,
UCLA, October 2010.

Categorification
and Low Dimensional Topology, Stony Brook University,
June 2010.

Knots,
Contact Geometry and Floer Homology, University of Tokyo, May
2010.

Introductory Workshop: Symplectic and Contact Geometry and Topology, Mathematical Sciences Research Institute, August 2009.
 Workshop on Mirror Symmetry, Symplectic Geometry, and Related Topics, MIT, June 2009.
 Georgia International Topology Conference, University of Georgia, May 2009.
 Special
session on low dimensional topology and geometry, AMS Southeastern Sectional Meeting, North Carolina State University, April 2009.
 Interactions of Geometry and Topology in Dimensions 3 and 4, Banff International Research Station, March 2009.
 Illinois/Indiana Symplectic Geometry Conference, University of Illinois at UrbanaChampaign, March 2009.
 AMS special session on categorification and link homology, Joint Mathematics Meetings, Washington, DC, January 2009.

Math
Institutes Modern Mathematics Workshop, Society for Advancement
of Chicanos and Native Americans in Science annual conference, Salt
Lake City, October 2008.

Legendrian
and Transverse Knots, American Institute of Mathematics,
September 2008.

Gökova
GeometryTopology Conference, Gökova, Turkey, May 2008.

Knots
in Washington XXVI, George Washington University, April 2008.

Towards Relative Symplectic Field Theory, CUNY, September 2007.

Communicating Mathematics, University of Minnesota at Duluth, July 2007.

Interactions of Geometry and Topology in Low Dimensions, Banff
International Research Station, March 2007.
 Low
Dimensional Topology, Research Program, Park City Mathematics Institute,
July 2006.
 Conference
on 3manifold Topology in honor of Peter Shalen,
Université de Montréal, June 2006.
 Workshop
“Around Khovanov homology”, Université du
Québec à Montréal, October 2005.
 Holomorphic
Curves workshop, Institute for Advanced Study, June 2005.
 Gökova
Geometry/Topology Conference, Gökova, Turkey, June 2005.
 The
Interaction of Finite Type and GromovWitten Invariants, Banff
International Research Station, November 2003.
 Holomorphic Curves in
Contact Geometry, American Institute of Mathematics, August
2003.
 Session on contact and symplectic geometry, AMS Eastern
Sectional Meeting, Courant Institute, April 2003.
 Symplectic
Geometry and Physics Workshop, Institute for Pure and Applied
Mathematics, UCLA, March 2003.
 Holomorphic
Curves and Low Dimensional Topology, Institute for Advanced
Study, March 2002.
 Session on symplectic and contact topology, AMS Southeastern
Sectional Meeting, Georgia Institute of Technology, March 2002.
 Georgia
International Topology Conference, University of Georgia, May
2001.
 Conference, Stanford
University/American Institute of Mathematics program in contact
geometry, Stanford University, December 2000.
Seminar talks

2013: Australian National University, UC Santa Barbara.

2011: MIT, Columbia University, Haverford College, Simons Center for
Geometry and Physics (Stony Brook).

2010: Princeton University.

2009: ETH Zürich (2).

2008: Stanford University, MIT.

2007: Columbia University (2), Princeton University, SUNY Stony Brook,
University of Virginia, MIT, Harvard University.

2006: University of Texas, Duke University.

2005: Bryn Mawr College/Haverford College, University of
CaliforniaBerkeley (2), Columbia
University (2), Georgia Institute of Technology, University of Wisconsin,
University of Southern California, University of Illinois at
UrbanaChampaign.

2004: University of Southern California/California Institute of
Technology, Stanford University.

2003: University of CaliforniaBerkeley, Stanford University,
University of Pennsylvania, Harvard University, Haverford College.

2002: Columbia University, Stanford University.

2001: University of North Carolina, Princeton University.

2000: Stanford University, Harvard University.
Service and miscellaneous

Organizer for the conferences: “Cyclic Homology and Symplectic
Topology”, American Institute of Mathematics, November 2009;
“Algebraic Structures in the Theory of Holomorphic Curves”,
Mathematical Sciences Research Institute, November 2009; “27th
Annual Geometry Festival”, Duke University, April 2012.

Organizer for the special sessions: “Low dimensional topology and
geometry”, AMS
Southeastern Sectional Meeting, North Carolina State University, April
2009; “Interactions of geometry and topology in low dimensions”, AMS
Southeastern Sectional Meeting, Tulane Unversity, October 2012.

Editor, Quantum Topology.
 Reviewed for: Mathematical Reviews; NSF grant panel;
Algebraic & Geometric Topology, Communications in Contemporary Mathematics,
Discrete Mathematics, Duke Mathematical Journal, Experimental Mathematics,
Geometry &
Topology, International Journal of Mathematics, International
Mathematics Research Notices, Journal of Differential Geometry,
Journal of the European Mathematical Society,
Journal of Graph Theory, Journal of Knot Theory and its
Ramifications, RoseHulman Undergraduate Mathematics Journal,
Topology and its Applications, Transactions of the American
Mathematical Society.

Member, Subcommittee for the United States Mathematical Olympiad,
Mathematical Association of America, 2009present.
 Instructor for Berkeley
Math Circle (for high school students),
2010; San
José Math Circle (for middle school students), 2006; Stanford Math Circle
(for high school students), 2005.
 Guest lecturer at Canada/USA
MathCamp (for high school students), 1997.
 Conducted several undergraduatelevel lectures as a staff member at the US Mathematical
Olympiad Summer Program, 1994 and 1995; helped maintain an online
archive of solutions for the Putnam Mathematical Competition
(since 1997).