CV

Education

  • Cornell University, Ithaca, NY
    • Ph.D. in Operations Research: May 1995
    • Major: Optimization
    • Minors: Computer Science; Statistics
    • Thesis: Parallel Branch and Cut for Vehicle Routing
    • Thesis advisor: Dr. Leslie E. Trotter, Jr.
  • Carnegie Mellon University, Pittsburgh, PA
    • M.S. in Mathematics and B.S. in Applied Mathematics (with University Honors): May 1991
    • Concentration: Operations Research

Current Positions

Previous Positions

  • Vice President, Research and Development, Scalable OR Solutions, June 2004 - June 2007
  • Assistant Professor, Industrial and Systems Engineering, Lehigh University, Bethlehem, PA, June 2000 - May 2006
  • Postdoctoral Research Associate, Rice University, Houston, TX, September 1999 - August 2000
  • United States Air Force, Nellis AFB, NV
    • Chief, Tactics and Test Analysis, June 1997 - May 1999
    • F-16 Lead Operations Analyst, June 1996 - May 1997
    • Manpower Management Officer, June 1995 - May 1996
  • Cornell University, Ithaca, NY
    • Research Assistant, Summer 1991-3, January 1994 - May 1995
    • Teaching Assistant, January 1992 - December 1993

Research Funding

Honors and Awards

Refereed Publications

  • M. Guzelsoy and T.K. Ralphs, Duality for Mixed-Integer Linear Programs, The International Journal of Operations Research 4 (2007), 118 (Working paper version: PS PDF).
  • T.K. Ralphs, Parallel Branch and Cut, in Parallel Combinatorial Optimization, E. Talbi, ed. (2006) (Working paper version: PS PDF)
  • T.K. Ralphs, M.J. Saltzman, and M.M. Wiecek, An Improved Algorithm for Biobjective Integer Programming, Annals of Operations Research 147 (2006), 43 (Working paper version: PS PDF).
  • T.K. Ralphs and M. Galati, Decomposition and Dynamic Cut Generation in Integer Programming, Mathematical Programming 106 (2006), 261 (Working paper version: PS PDF) (Extended abstract: PS PDF).
  • J.T. Linderoth and T.K. Ralphs, Noncommercial Software for Mixed-Integer Linear Programming, in Integer Programming: Theory and Practice, John Karlof, ed. (2005), 253 (Working paper version: PS PDF).
  • T.K. Ralphs and M. Galati, Decomposition in Integer Programming, in Integer
    Programming: Theory and Practice    , John Karlof, ed. (2005), 57 (Working paper version: PS PDF).
  • T.K. Ralphs and M. Guzelsoy, The SYMPHONY Callable Library for Mixed Integer Programming, The Proceedings of the Ninth INFORMS Computing Society Conference (2005), 61 (Working paper version: PS PDF).
  • Y. Xu, T.K. Ralphs, L. Ladányi, and M.J. Saltzman, ALPS: A Framework for Implementing Parallel Search Algorithms, The Proceedings of the Ninth INFORMS Computing Society Conference (2005), 319
    (Working paper version: PS PDF).
  • T.K. Ralphs, L. Ladányi, and M.J. Saltzman, A Library Hierarchy for Implementing Scalable Parallel Search Algorithms, The Journal of Supercomputing 28 (2004), 215 (Working paper version: PS PDF).
  • T.K. Ralphs, L. Ladányi, and M.J. Saltzman, Parallel Branch, Cut, and Price for Large-scale Discrete Optimization, Mathematical Programming 98 (2003), 253 (Working paper version: PS PDF).
  • T.K. Ralphs, Parallel Branch and Cut for Capacitated Vehicle Routing, Parallel Computing 29 (2003), 607 (Working paper version: PS PDF).
  • T.K. Ralphs, L. Kopman, W.R. Pulleyblank, and L.E. Trotter Jr., On the Capacitated Vehicle Routing Problem, Mathematical Programming 94 (2003), 343 (Working paper version: PS PDF).
  • L. Ladányi, T.K. Ralphs, and M.J. Saltzman, Implementing Scalable Parallel Search Algorithms for Data-intensive Applications, The Proceedings of the International Conference on Computational Science (2002), Volume I, 592 (Working paper version: PS PDF).
  • L. Ladányi, T.K. Ralphs, and L.E. Trotter Jr., Branch, Cut, and Price: Sequential and Parallel, in Computational Combinatorial Optimization, D. Naddef and M. Juenger, eds., Springer, Berlin (2001), 22. (PS PDF).
  • M. Esö, L. Ladányi, T.K. Ralphs, and L.E. Trotter Jr., Fully Parallel Generic
    Branch-and-Cut Framework    , Proceedings of the 8th SIAM Conference on Parallel Processing for Scientific
    Computing (1997).
  • T.K. Ralphs, On the Mixed Chinese Postman Problem, Operations Research Letters 14 (1993), 123 (Working paper version: PS PDF).

Technical Reports and Publications In Review

  • Z. Akca, R. Berger, and T.K. Ralphs, A Branch-and-Price Algorithm for Combined Location and Routing Problems Under Capacity Restrictions, COR@L Laboratory Technical Report (2008) (PDF)
  • A. Mahajan and T.K. R.=alphs, Experiments with Branching on General Hyperplanes, COR@L Laboratory Technical Report (2008) (PDF)
  • M. Guzelsoy and T.K. Ralphs, The Value Function of a Mixed-Integer Linear Program with a Single Constraint, COR@L Laboratory Technical Report (2008) (PDF)
  • S. DeNegre and T.K. Ralphs, A Branch-and-cut Algorithm for Integer Bilevel Linear Programs, COR@L Laboratory Technical Report (2008) (PDF).
  • M. Guzelsoy and T.K.Ralphs, The Value Function of a Mixed-Integer Linear Program with a Single Constraint, COR@L Laboratory Technical Report (2008) (PDF)
  • S. DeNegre and T.K. Ralphs, A Branch-and-cut Algorithm for Integer Bilevel Linear Programs, COR@L Laboratory Technical Report (2007) (Available by request).
  • O. Osaltyn, B. Hunsaker, and T.K.Ralphs, Visualizing Branch-and-Bound Algorithms, COR@L Laboratory Technical Report (2007) (PDF).
  • Y. Xu, T.K. Ralphs, L. Ladányi, and M.J. Saltzman, Computational Experience with a Software Framework for Parallel Integer Programming, COR@L Laboratory Technical Report (2007) (PDF).
  • T.K. Ralphs, SYMPHONY Version 5.1 User’s Manual, COR@L Laboratory Technical Report (2006) (PDF).
  • T.K. Ralphs and M. Guzelsoy, Duality and Warm Starting in Integer Programming, Proceedings of the 2006 NSF Design, Service, and Manufacturing Grantees and Research Conference (PS) ( PDF).
  • T.K. Ralphs and M. Guzelsoy, Duality, Warm Starting, and Sensitivity Analysis in Integer Programming, Lehigh University Industrial and Systems Engineering Technical Report 04T-021 (2004) (Available by request).
  • R. Lougee-Heimer, M. Saltzman, and T.K. Ralphs, ‘COIN’ of the OR Realm, OR/MS Today, October 2004.
  • T.K. Ralphs, SYMPHONY Version 5.0 User’s Manual, Lehigh University Industrial and Systems Engineering Technical Report 04T-020 (2004) (PS PDF).
  • T.K. Ralphs, M.J. Saltzman, and M.M. Wiecek, An Improved Algorithm for Biobjective Integer Programming and Its Application to Network Routing Problems, Lehigh University Industrial and Systems Engineering Technical Report 04T-004 (2004) (PS PDF).
  • T.K. Ralphs, SYMPHONY Version 4.0 User’s Manual, Lehigh University Industrial and Systems Engineering Technical Report 03T-006 (2003) (PS PDF).
  • L. Ladányi, T.K. Ralphs, and M.J. Saltzman, A Library Hierarchy for Implementing Scalable Parallel Search Algorithms, Lehigh University Industrial and Systems Engineering Technical Report 01T-010 (2001) (PS PDF).
  • T.K. Ralphs and J.C. Hartman, Capacitated Network Routing (A Preliminary Progress Report), Lehigh University Industrial and Systems Engineering Working Paper 01W-009 (2001) (PS PDF).
  • R. Lougee-Heimer, et al., The COIN-OR Initiative: Open-source software accelerates operations research progress, OR/MS Today, October 2001.
  • T.K. Ralphs and L. Ladányi, COIN/BCP User’s Manual (2001) (PS PDF).
  • T.K. Ralphs and L. Ladányi, SYMPHONY: A Framework for Parallel Branch, Cut, and Price, White paper, Rice University (1999) (PS PDF).
  • T.K. Ralphs, W.R. Pulleyblank, and L.E. Trotter Jr., On Capacitated Vehicle Routing , CCOP Technical Report 98-7, Cornell University, School of ORIE, Ithaca, NY (1998) (PS (g’zipped)).
  • T.K. Ralphs, Parallel Branch and Cut for Vehicle Routing, PhD. Thesis, May 1995.

Software

  • CHiPPS: The COIN High Performance Parallel Search Framework
    This C++ class library and framework for implementing parallel search algorithms for large-scale, data-intensive applications consist of three layers.
    • ALPS: Abstract Library for Parallel Search
      ALPS provides the base infrastructure for implementing a variety of search algorithms, such as branch and bound or constraint logic programming. Two prototype solvers, a vanilla branch-and-cut solver and a knapsack problem solver, have been derived from ALPS to demonstrate its use.
    • BiCePS: Branch, Constrain, and Price Software
      Built on top of ALPS, BiCePS provides the data layer for implementing relaxation-based optimization algorithms, such as LP-based branch and bound. Scalability is maintained through the use of compact data structures for storage and communication of problem data.
    • BLIS: BiCePS Linear Integer Solver
      This C++ class library is a concretization of BiCePS for the case of mixed-integer linear programming based on LP relaxation.
  • OSI: The Open Solver Interface
    The Open Solver Interface provides a uniform application program interface (API) for third-party solvers that allows the development of applications that do not depend on the availability of a particular solver (so-called solver agnostic applications). The second generation of OSI is currently under development and will provide classes for building models, in addition to classes for passing these models to solvers.
  • SYMPHONY: Single- or Multi-Process Optimization over Networks
    An open-source, generic MILP solver, callable library, and extensible framework for implementing customized MILP solvers, SYMPHONY can be built in various sequential and parallel configurations for either distributed or shared memory architectures. SYMPHONY has a number of advanced capabilities stemming from the research projects discussed above, including the ability to solve multi-objective MILPs, the ability to warm start its solution procedure, and the ability to perform basic sensitivity analyses. SYMPHONY has an active user community and has been deployed in a variety of application areas, including computational biology, wireless telecommunications, supply chain management, transportation services, and air transportation. It can be used “out of the box” as a solver for generic mixed-integer linear programs or customized for a particular application through the use of numerous callback functions.
  • DECOMP
    A software framework for implementing bounding methods for integer programs based on the integrations of traditional decomposition methods with polyhedral methods.

Conference Presentations

Seminar Presentations

  • T.K. Ralphs, Y. Xu, L. Ladanyi, and M.Saltzman, Doing it in Parallel (DIP) with the COIN-OR High Performance Parallel Search Framework (CHiPPS), Graduate Research Seminar, Pennsylvania State University, April, 2008.
  • T.K. Ralphs and M. Guzelsoy, The Value Function of a Mixed Integer Program with a Single Constraint, COPTA Seminar, University of Wisconsin-Madison, February, 2008.
  • T.K. Ralphs, M. Guzelsoy, J.T. Linderoth, M.J. Saltzman, and M. Wiecek, Biobjective Integer Programming, SAS Institute , June 2006. (PS PDF).
  • T.K. Ralphs, M. Guzelsoy, M. Saltzman, and M. Wiecek, Bioobjective Integer Programming, Rutgers University, Department of Industrial and Systems Engineering, Piscataway, NJ, October 2005 (PS PDF).
  • T.K. Ralphs and M. Guzelsoy, Duality, Sensitivity Analysis, and Warm Starting, SAS Institute , August 2005. (PS PDF).
  • T.K. Ralphs, Making Molehills out of Mountains: A Guided Tour of Large-scale Discrete Optimization, Mathematics Department Colloquium, April 2005. (PS PDF).
  • T.K. Ralphs, Capacitated Vehicle Routing and Some Related Problems, Computer Science and Engineering Seminar Series, March 2005. (PS PDF).
  • T.K. Ralphs, Integer Programming: A Research Overview , Lehigh IGERT Seminar, September 2004. (PS PDF).
  • T.K. Ralphs, Integer Programming: A Research Overview , Lehigh IGERT Seminar, September 2003. (PS PDF).
  • T.K. Ralphs, Solving Hard Combinatorial Problems: A Research Overview , Lehigh IGERT Seminar, October 2002. (PS PDF).
  • T.K. Ralphs, L. Ladányi, and M.J. Saltzman, A New Framework for Scalable Parallel Tree Search, Lehigh ISE Optimization Seminar, September 2002. (PS PDF).
  • T.K. Ralphs, Solving Hard Combinatorial Problems: A Research Overview, Process Modeling and Control Seminar, Department of Chemical Engineering, Lehigh University, March 2002(PS PDF).
  • T.K. Ralphs, Decomposition-based Algorithms for Large-scale Discrete Optimization, National University of Singapore, March 2002 (PS PDF).
  • T.K. Ralphs, Capacitated Vehicle Routing and Some Related Problems, Rutgers University, Department of Industrial and Systems Engineering, Piscataway, NJ, November 2001 (PS PDF).
  • T.K. Ralphs, L. Ladányi, and M.J. Saltzman, A Library Hierarchy for Implementing Scalable Parallel Search Algorithms, Rutgers Center for Operations Research (RUTCOR), Rutgers University, Piscataway, NJ, Sepember 2001. (PS PDF).
  • T.K. Ralphs, Branch, Cut, and Price Algorithms for Large-scale Discrete Optimization, National University of Singapore, August 2001 (PS PDF).
  • T.K. Ralphs and J.C. Hartman, Capacitated Network Routing, National University of Singapore, August 2001 (PS PDF).
  • T.K. Ralphs, L. Ladányi, and M.J. Saltzman, A Library Hierarchy for Implementing Scalable Parallel Search Algorithms, IBM T.J. Watson Research Center, Yorktown Heights, NY, August 2001 (PS PDF).
  • T.K. Ralphs, Decomposition-based Algorithms for Discrete Optimization
    , IBM T.J. Watson Research Center, Yorktown Heights, NY, August 2001. (slides available by request).
  • T.K. Ralphs and J.C. Hartman, Capacitated Network Routing , IBM T.J. Watson Research Center, Yorktown Heights, NY, July 2001 (PS PDF).
  • T.K. Ralphs, W. Pulleyblank, and L.E. Trotter Jr., A New Generic Separation Algorithm for Combinatorial Optimization, IBM T.J. Watson Research Center, Yorktown Heights, NY, November 1999 (PS PDF).
  • T.K. Ralphs, Polyhedral Aspects of the Mixed Postman Problem, Cornell Computational Optimization Project Colloquium, Ithaca, NY, February 1994.
  • T.K. Ralphs and L. Ladányi, Computational Experience with a New Heuristic for the Crew Scheduling Problem, Cornell Computational Optimization Project Colloquium, Ithaca, NY, October 1993.

Conference Sessions Chaired

  • Open Source MIP Solvers, The Institute for Operations Research and Management Science Conference, Seattle, WA, November 2007.
  • Modeling Languages in the Classroom, The Institute for Operations Research and Management Science Conference, Seattle, WA, November 2007.
  • Optimization Software in the Classroom, The Institute for Operations Research and Management Science Conference, Seattle, WA, November 2007.
  • Open Source Modeling Tools, The Institute for Operations Research and Management Science Conference, San Francisco, CA, November 2005.
  • Integer Programming Software, Institute for Operations Research and Management Science Annual Conference, Denver, CO, October 2004.
  • COIN-OR: Software Tools for Optimization, CORS/INFORMS Joint International Meeting, Banff, Alberta, Canada, May 2004.
  • Computational Mixed-Integer Programming, CORS/INFORMS Joint International Meeting, Banff, Alberta, Canada, May 2004.
  • Open Source Optimization Tools, CORS/INFORMS Joint International Meeting, Banff, Alberta, Canada, May 2004.
  • COIN-OR: Software Tools for Implementing Custom Solvers , the Institute for Operations Research and Management Science Annual Conference, Atlanta, GA, October 2003.
  • Decomposition and Dynamic Cut Generation, the International Symposium on Mathematical Programming, Copenhangen, Denmark, August 2003.
  • COIN-OR: Software Tools for Implementing Custom Solvers , the International Symposium on Mathematical Programming, Copenhangen, Denmark, August 2003.
  • Standards and Interfaces in Mathematical Programming, The Institute for Operations Research and Management Science Annual Conference, San Jose, CA, November 2002.
  • Software Tools for Parallel Processing, The Institute for Operations Research and Management Science Annual Conference, San Jose, CA, November 2002.
  • Workshop: Software Tools for Implementing Branch, Cut, and Price Algorithms, The Institute for Operations Research and Management Science Annual Conference, San Jose, CA, November 2002.
  • Branch and Cut Methods , The Institute for Operations Research and Management Science Annual Conference, Miami, FL, November 2001.
  • Parallel Discrete Optimization with Applications , International Symposium on Mathematical Programming, Georgia Institute of Technology, August 2000.

Conference Clusters Chaired

  • Integer Programming, The INFORMS Computing Society Conference, Charleston, SC, January, 2009.
  • Computational Optimization and Software, The Institute for Operations Research and Management Science Annual Conference, Washington, D.C., October 2008.
  • Optimization Services and Open Source Software, The Institute for Operations Research and Management Science Conference, San Francisco, CA, November 2005.

Conference Program Committees

  • International Workshop of the EURO Working Group on Parallel Processing in Operations Research, Mont Tremblant, CA, January 2005.

Student Supervision

  • Ph.D Dissertation Advisor and Committee Chair
    • Matthew Galati, ISE, Decomposition Algorithms for Large-scale Discrete Optimization.
    • Svetlana Oshkai, ISE, Winner Determination in Combinatorial Auctions.
    • Menal Guzelsoy, ISE, Duality, Warm Starting, and Sensitivity Analysis in Mixed-Integer Programming.
    • Scott Denegre, ISE, On Mixed Integer Bilevel Programming and Mixed Integer Interdiction.
    • Ashutosh Mahajan, ISE, Heuristic Methods in Mixed Integer Linear Programming.
    • Zeliha Akca, ISE, Integrated Location, Routing, and Scheduling Problems: Models and Algorithms.
    • Ali Pilatin, ISE, TBD.
    • Yan Xu, ISE, Scalable Algorithms for Parallel Tree Search, December 2007.
  • Ph.D Dissertation Committee Chair
    • Jerry Shen, ISE, Solving Multi-stage Stochastic Linear Programs on the Computational Grid.
    • Wasu Glankwamdee, ISE, Branch and Bound on Computational Grids.
    • Jim Ostrowski, ISE, Symmetry in Mixed Integer Programming.
    • Kumar Abhishek, ISE, Topics in Mixed Integer Nonlinear Programming, May 2008.
  • Ph.D Dissertation Committee Member
    • Udom Janjarassuk, ISE, Using the Computational Grid for the Effective Solution of Stochastic Programs.
    • Zhengxiang Pan, CSE, Towards a Global Scale Semantic Web.
    • Qing Ye, CSE, Dynamic Multicast and Time Synchronization in Wide-area Sensor Networks, December 2007.
    • Brian Heinold, Mathematics, Sum List Coloring and Choosability, May 2006.
    • Joao Goncalves, ISE, Extensions of von Neumann’s Algorithm for Linear Programming, May 2005.
    • Lilong Huang, Chemical Engineering, Constrained Closed-loop Optimal Control, May 2005.
    • Jinlong Ban, ISE, Lehigh University, The Generalized Parallel Replacement Problem, December 2003.
  • M.S. Advisor
    • Shelley Heist, ISE, Lehigh University, Constraint Programming and Sourcing Problems, May 2003.
    • Andrew Hofmann, ISE, Lehigh University, The Mixed Postman Problem, May 2003.

Student Awards

  • ISE graduate student of the year
    • Matthew Galati, 2003
    • Menal Guzelsoy, 2004
  • Lehigh Engineering Ingenuity Award for Graduate Research and Scholarship
    • Matthew Galati, 2004
    • Menal Guzelsoy, 2005
  • Computational Interface for Operations Research Open Source Coding Contest
    • Yan Xu, First Place, 2003
  • First Open Contest of Parallel Coding
    • Yan Xu and Ted Ralphs, First Place, 2007

Courses Developed and Taught

Service

  • University
    • Computational Optimization Research at Lehigh (COR@L) Laboratory, co-founder and director, September 2004 - present.
    • Lehigh High Performance Computing Steering Committee, co-founder and chairman, January 2004 - present.
    • Mathematics Search Committee, member, September 2005 - May 2006.
  • College
    • CSE Faculty Search Committee, member, September 2007 - present.
    • ISE Department Chair Search Committee, member, April 2007 - present.
    • RCEAS Dean’s Research Advisory Council, member, January 2007 - present.
    • RCEAS Engineering Ingenuity Awards Committee, member, April 2005.
    • RCEAS Computational Sciences Committee, member, September 2001 - May 2003.
    • RCEAS Mathematics Curriculum Review Committee, member, September 2001 - May 2003.
    • RCEAS Freshman Advisor, September 2002 - May 2003.
    • Molecular Modeling Search Committee, member, September 2002 - May 2003.
    • Chemical Engineering Search Committee, member, September 2001 - May 2002.
  • Department
    • Co-director of Graduate Programs.
    • Lehigh Student Chapter of the Institute for Operations Research and Management Science, first faculty advisor, July 2005 - present.
    • ISE Optimization Seminar Series (now the COR@L Seminar Series), founder and organizer, September 2002 - present.
    • ISE Graduate Curriculum Committee, member, September 2001 - present.
    • ISE Council, member, September 2001 - May 2003, September 2004 - present.
    • ISE Information and Systems Engineering Curriculum Development Committee, chairman, September 2001 - May 2003.
    • ISE Search Committee, member, various times September 2000 - May 2006.

Professional Activities

  • CORAL Optimization Seminar Series, founder and co-organizer.
  • Founder and webmaster of BranchAndCut.org.
  • COIN-OR Foundation, founding board member, treasurer, and chair of the Technical Leadership Council.
  • Associate Editor, Operations Research Letters.
  • Associate Editor, Operations Research.
  • Technical Editor, Mathematical Programming Computation.
  • Editorial Board, Algorithmic Operations Research.
  • Publication Referee
    • Computers and Operations Research
    • Computational Optimization and Applications
    • Discrete Optimization
    • Discrete Mathematics
    • European Journal of Operations Research
    • IEEE Control Systems Society
    • IEEE Transactions on Computers
    • INFORMS Journal of Computing
    • International Journal of Operations Research
    • International Journal of Computer Mathematics
    • International Transactions in Operations Research
    • Mathematical Programming
    • Networks
    • Operations Research
    • Operations Research Letters
    • Optimization Letters
    • Optimization Methods and Software
    • Parallel Computing
    • The Open Operational Research Journal
    • Transportation Science
  • Proposal Reviewer
    • National Science Foundation
    • U.S. Civilian Research and Development Foundation
  • Institute for Operations Research and Management Science, member.
  • INFORMS Computing Society, member.
    • INFORMS Computing Society Membership Committee, member.
  • INFORMS Optimization Section, Vice Chair for Computational Optimization and Software.
  • Mathematical Programming Society, member.
  • Former president of the Cornell Operations Research Graduate Association.
  • Founding member and first president of the Cornell Graduate and Professional Student Assembly.
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