- Associate Professor
- Associate Professor, Department of Mathematics

**Background:** Henning Mortveit is an Associate Professor in the Network Dynamics and Simulation Science Laboratory at the Biocomplexity Institute of Virginia Tech as well as an Associate Professor in the Department of Mathematics. He received his doctorate in mathematics from the Norwegian University of Science and Technology in 2000, and spent five years at the Los Alamos National Laboratory before joining Virginia Tech in 2005. He leads the NDSSL software team and the synthetic information work.

**Research: **How can we make a city and its physical infrastructures more resilient? How can existing infrastructures be modified to make a city more robust with respect to disasters? How do we start to reason about these questions?

Modern cities are examples of highly complex systems that can be captured as massively interacting systems whose network components co-evolve with time. To capture these systems in a precise mathematical manner is a challenge that must address:

- modeling power;
- ability to analytically analyze and validate mathematical models;
- ability to efficiently implement models (construct simulation models) on current, high performance hardware;
- scalability to accommodate simulation analysis needs quickly.

His research involves all of these aspects. The work is centered around the framework of Graph Dynamical Systems (GDS). This class of dynamical systems was introduced as a natural mathematical framework that permits precise modeling of *massively interacting systems. *They address all of the points above permitting mathematical analysis, modeling, efficient implementions and rigorous verification & validation. Examples of such systems captured by GDS include socio-technical systems (interconnected physical networks and infrastructures, their inter-dependencies, as well as the interplay with human behavior), biological systems, and general distributed systems. Specific research topics include:

**GDS fundamental theory:** structure-to-function analysis, in particular stability analysis as it pertains to sensitivity analysis, uncertainty quantification and validation. Brute force computations are usually intractable as far as computations go, so this work is about gaining insight about behavior using mathematical theory. Examples of questions include:

- If vertex functions (the way system entities operate) are perturbed, will system behavior change significantly?

- If the network has certain properties (e.g. those characteristic of a power grid), can we guarantee that all dynamics terminate at a steady state?

**Critical infrastructure and societal resilience:** How does one plan for disaster handling? How does one identify the best or most cost-efficient ways to protect infrastructures and their operation? This work focuses on modeling of infrastructures, their interconnections, human behavioral effects, and on mapping these into validated, scalable simulation models capable of informing policy makers.

**Software and system design for scalable, scientific computing:** ensuring scientifically reproducible computation for large scale simulation models is a big challenge. Tracking all data sources, their provenance, their transformations to fit required input formats, the tracking of the tools and algorithms used to transform the data, as well as the simulation models used give rise to a host of challenges. This work addresses this problem as well as efficient ways to add and combine simulation models for innovative and rapid modeling and analysis with integrated validation and data quality assessments.

**Visualization**: scientific visualization of spatial phenomena, in particular for illustrations of dynamics of large, interaction-based systems involving synthetic information.

**GDS models on specialized hardware** (dormant): acceleration of simulation models by implementing computation-intensive componets on hardware like field programmable gate arrays (FPGAs).

- Wu S, Mortveit HS, Gupta S. A Framework for Validation of Large-Scale, Computer Simulation Models: An Application to Networked Epidemics. In:
*Proceedings of the ACM SIGSIM Conference on Principles of Advanced Discrete Simulation (PADS)*. 2017. https://doi.org/10.1145/3064911.3064922. - Adiga A, Galyean H, Kuhlman CJ, Levet M, Mortveit HS, Wu S. Network Structure and Activity in Boolean Networks. In:
*Proceedings of the 21st International Workshop on Cellular Automata and Discrete Complex Systems*. Vol 8155. 2015:210-223. https://doi.org/10.1007/978-3-662-47221-7_16. - Wu S, Adiga A, Mortveit HS. Limit cycle structure for dynamic bi-threshold systems.
*Theoretical computer science*. 2014;559:34-41. http://www.sciencedirect.com/science/article/pii/S03043975140050.... - Adiga A, Marathe MV, Mortveit HS, Wu S, Swarup S. Modeling Urban Transportation in the Aftermath of a Nuclear Disaster: The Role of Human Behavioral Responses. In:
*Transportation Research: Part C (International Journal of Transportation)*. 2013. - Mortveit HS, Murrugarra D, Kuhlman CJ, Kumar VSA. Bifurcations in Boolean Networks.
*Discrete Mathematics and Theoretical Computer Science, Proceedings of the 17th International Workshop on Cellular Automata and Discrete Complex Systems*. 2011;AP:29-46. http://www.automata2011.dim.uchile.cl/. - Tripp J, Hansson A, Gokhale M, Mortveit HS. Partitioning hardware and software for reconfigurable supercomputing applications: A case study. In:
*Proceedings of the 2005 ACM/IEEE Conference on Supercomputing '05 Industrial*. 2005:27-38. https://doi.org/10.1109/SC.2005.54. - Macauley M, Mortveit HS. Cycle equivalence of graph dynamical systems.
*Nonlinearity*. 2009;22(2):421-436. https://doi.org/10.1088/0951-7715/22/2/010. - Macauley M, McCammond J, Mortveit HS. Order independence in asynchronous cellular automata.
*Journal of Cellular Automata*. 2008;3(1):37-56. http://arxiv.org/abs/0707.2360. - Macauley M, Mortveit HS. Posets from Admissible Coxeter Sequences.
*The Electronic Journal of Combinatorics*. 2011;18(1):#P197. http://www.combinatorics.org/Volume_18/PDF/v18i1p197.pdf.

- Norwegian University of Science and Technology, Mathematics, Ph.D., 2000
- Norwegian Institute of Technology, Mathematics, MS, 1995

- Los Alamos National Laboratory, Mathematics and Simulation, Postdoctoral Associate, 2000-2002
- Los Alamos National Laboratory, Mathematics and Simulation, Staff member, 2002-2005