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Mark Haskins
Professor of Mathematics

My research concerns problems at the intersection between

I am currently the Deputy Director of the Simons Collaboration Special Holonomy in Geometry, Analysis, and Physics . My colleague here at Duke, Robert Bryant, is the Collaboration Director and currently Chair of the Mathematics department.

Currently, I am particularly interested in special types of 7-dimensional spaces called

Manifolds with special holonomy also come equipped with special submanifolds, called

**Differential Geometry**and**Partial Differential Equations**, particularly special geometric structures that arise in the context of holonomy in Riemannian geometry.I am currently the Deputy Director of the Simons Collaboration Special Holonomy in Geometry, Analysis, and Physics . My colleague here at Duke, Robert Bryant, is the Collaboration Director and currently Chair of the Mathematics department.

Currently, I am particularly interested in special types of 7-dimensional spaces called

**G**, or G_{2}-holonomy manifolds_{2}-manifolds for short. These spaces also arise naturally in modern theoretical physics in the 11-dimensional theory known as M theory. To get from 11 dimensions down to 4 dimensions it is necessary to 'compactify' on a 7-dimensional space and to preserve the maximal degree of (super)symmetry this 7-dimensional space should have G_{2}-holonomy. In fact, realistic 4-dimensional physics appears to demand singular G_{2}-holonomy spaces and trying to construct compact singular G_{2}-holonomy spaces is one of my current research projects.Manifolds with special holonomy also come equipped with special submanifolds, called

**calibrated submanifolds**, and special connections on auxiliary vector bundles, called generalised instantons. I am particuarly interested in**associative**and**coassociative submanifolds**in G_{2}-holonomy spaces and**special Lagrangian submanifolds**in Calabi-Yau spaces. In the past I have also studied*singular*special Lagrangian n-folds.### Current Research Interests

- Riemannian geometry
- Systems of elliptic partial differential equations
- Einstein manifolds, especially Ricci-flat manifolds
- Riemannian metrics with special or exceptional holonomy.
- Minimal submanifolds, particularly calibrated submanifolds
- Calibrated currents and their singularities and regularity, especially special Lagrangian and associative currents
- Singular spaces with special or exceptional holonomy
- Gauge theory on spaces with special and exceptional holonomy
- Riemannian collapse under Ricci-curvature bounds
- Solitons and singularity formation in in geometric flows, especially Bryant's Laplacian flow
- Heat and other parabolic equation methods for PDEs on manifolds

Some of my most recent research relates to a geometric flow of closed G

_{2}-structures, called the

**Laplacian flow.**Laplacian flow was introduced by Bryant as a way to try to flow a closed G

_{2}-structure to a torsion-free G

_{2}-structure. As with many geometric flows, when curvature concentrates too fast the nonlinearity of the equation can overwhelm its diffusive tendencies and finite-time singularities can form. In certain geometric flows, like the Ricci flow and Mean Curvature Flow, singularity formation has long been a topic of intensive research and in some cases, like Ricci flow on 3-manifolds, it is largely understood.

The study of singularity formation in Laplacian flow is, however, still in its infancy. The first step to understanding singularity formation in geometric flows is often to study special types of self-similar solutions to the flow, called

**solitons.**With various collaborators, I've been trying to understand solitons in Laplacian flow, as a stepping stone toward understanding finite-time singularity formation in Laplacian flow.

In this preprint, Johannes Nordstrom and I studied highly symmetric Laplacian solitons. We found a pair of shrinking Laplacian solitons and a 1-parameter family of steady Laplacian solitons, all with asymptotically conical geometry. The asymptotically conical steady solitons are a distinctive feature of Laplacian flow, since such solutions cannot arise in Ricci flow.

In this preprint , my Duke postdoc Alec Payne and our Oxford collaborator Ilyas Khan proved that any asymptotically conical Laplacian shrinker is uniquely determined by its conical end. This is proven by establishing a suitable backwards uniqueness existence result for asymptotically conical solutions to Laplacian flow.

### Current Appointments & Affiliations

- Professor of Mathematics, Mathematics, Trinity College of Arts & Sciences 2019

### Contact Information

- 120 Science Drive, 117 Physics Building, Campus Box 90320, Durham, NC 27708-0320
- 187 Physics Building, 120 Science Drive, West Campus, Durham, NC 27708-0320
- mhaskins@math.duke.edu
- Haskins webpage
- Special Geometric Structures and Analysis@MSRI/SLMath Fall 2024
- Find out what the Simons Collaboration on Special Holonomy is all about
- Journal of the London Mathematical Society
- Learned Society of Wales
- My Mathematical Genealogy
- My lectures in the Simons Collaboration
- My mathematical genealogy II
- Publications and citations from Google Scholar
- Simons Collaboration on Special Holonomy in Geometry, Analysis and Physics

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