Research

Publications

The methods in SHOT are described in peer-reviewed papers. If you use SHOT in your research, please cite it.

Cite SHOT

The SHOT papers

Please cite these papers if you use SHOT in your research. The first describes the solver; the second describes its features for nonconvex problems.

  1. 2022

    The supporting hyperplane optimization toolkit for convex MINLP

    A. Lundell, J. Kronqvist, T. Westerlund

    Journal of Global Optimization, 84(1), 1–41

    doi:10.1007/s10898-022-01128-0 Open access

  2. 2022

    Polyhedral approximation strategies for nonconvex mixed-integer nonlinear programming in SHOT

    A. Lundell, J. Kronqvist

    Journal of Global Optimization, 82(4), 863–896

    doi:10.1007/s10898-021-01006-1 Open access

shot.bib
@article{Lundell2022SHOT,
  author  = {Lundell, Andreas and Kronqvist, Jan and Westerlund, Tapio},
  title   = {The supporting hyperplane optimization toolkit for convex {MINLP}},
  journal = {Journal of Global Optimization},
  volume  = {84},
  number  = {1},
  pages   = {1--41},
  year    = {2022},
  doi     = {10.1007/s10898-022-01128-0}
}

@article{Lundell2022Nonconvex,
  author  = {Lundell, Andreas and Kronqvist, Jan},
  title   = {Polyhedral approximation strategies for nonconvex mixed-integer
             nonlinear programming in {SHOT}},
  journal = {Journal of Global Optimization},
  volume  = {82},
  number  = {4},
  pages   = {863--896},
  year    = {2022},
  doi     = {10.1007/s10898-021-01006-1}
}

Both papers in BibTeX, ready for your bibliography. Both are open access.

Methods

SHOT and its algorithms

  1. 2019

    A center-cut algorithm for quickly obtaining feasible solutions and solving convex MINLP problems

    J. Kronqvist, D. E. Bernal, A. Lundell, T. Westerlund

    Computers & Chemical Engineering, 122, 105–113

    doi:10.1016/j.compchemeng.2018.06.019

  2. 2019

    Integration of polyhedral outer approximation algorithms with MIP solvers through callbacks and lazy constraints

    A. Lundell, J. Kronqvist

    AIP Conference Proceedings, 2070, 020012

    doi:10.1063/1.5089979

  3. 2019

    On solving nonconvex MINLP problems with SHOT

    A. Lundell, J. Kronqvist

    Optimization of Complex Systems: Theory, Models, Algorithms and Applications (WCGO 2019), Advances in Intelligent Systems and Computing, 991, 448–457

    doi:10.1007/978-3-030-21803-4_45

  4. 2019

    Convex MINLP – an efficient tool for design and optimization tasks?

    J. Kronqvist, A. Lundell

    Computer Aided Chemical Engineering, 47, 245–250

    doi:10.1016/b978-0-12-818597-1.50039-4

  5. 2018

    Reformulations for utilizing separability when solving convex MINLP problems

    J. Kronqvist, A. Lundell, T. Westerlund

    Journal of Global Optimization, 71(3), 571–592

    doi:10.1007/s10898-018-0616-3

  6. 2017

    SHOT – a global solver for convex MINLP in Wolfram Mathematica

    A. Lundell, J. Kronqvist, T. Westerlund

    Computer Aided Chemical Engineering, 40, 2137–2142

    doi:10.1016/b978-0-444-63965-3.50358-5

  7. 2017

    A center-cut algorithm for solving convex mixed-integer nonlinear programming problems

    J. Kronqvist, A. Lundell, T. Westerlund

    Computer Aided Chemical Engineering, 40, 2131–2136

    doi:10.1016/b978-0-444-63965-3.50357-3

  8. 2016

    The extended supporting hyperplane algorithm for convex mixed-integer nonlinear programming

    J. Kronqvist, A. Lundell, T. Westerlund

    Journal of Global Optimization, 64(2), 249–272

    doi:10.1007/s10898-015-0322-3

Workshops

Workshop papers

Short papers from the Global Optimization Workshop series (GOW, HUGO and STOGO).

  1. 2025

    Upcoming features in SHOT 2.0

    A. Lundell, A. Olama, J. Blomqvist, J. Ekman, J. Kronqvist

    Stockholm Global Optimization Workshop (STOGO 2025), 129–132

  2. 2025

    Improved bounding techniques for nonconvex MINLP in SHOT

    J. Blomqvist, A. Lundell

    Stockholm Global Optimization Workshop (STOGO 2025), 133–136

  3. 2025

    A parallel framework for primal heuristics in SHOT

    A. Olama, A. Lundell

    Stockholm Global Optimization Workshop (STOGO 2025), 137–140

  4. 2025

    Separating hyperplanes for mixed-integer polynomial optimization problems

    C. Eggen, J. Kronqvist, A. Lundell, S. Volkwein

    Stockholm Global Optimization Workshop (STOGO 2025), 199–202

  5. 2022

    Eigendecomposition-based reformulations for convex MINLP in the SHOT solver

    J. Kronqvist, A. Lundell

    Hungarian Global Optimization Workshop (HUGO 2022), 107–110

  6. 2022

    On solving MINLP problems with nonconvex signomials in SHOT

    A. Lundell, J. Kronqvist

    Hungarian Global Optimization Workshop (HUGO 2022), 129–132

  7. 2016

    Improvements to the supporting hyperplane optimization toolkit solver for convex MINLP

    A. Lundell, J. Kronqvist, T. Westerlund

    XIII Global Optimization Workshop (GOW’16), 101–104

  8. 2016

    Lifted polyhedral approximations in convex mixed integer nonlinear programming

    J. Kronqvist, A. Lundell, T. Westerlund

    XIII Global Optimization Workshop (GOW’16), 117–120

  9. 2014

    An extended supporting hyperplane algorithm for convex MINLP problems

    A. Lundell, J. Kronqvist, T. Westerlund

    XII Global Optimization Workshop (GOW’14), 21–24

Preprints

Recent preprints

Work that is part of, or builds on, SHOT 2.0.

  1. 2026

    Decomposition-based reformulation of nonseparable quadratic expressions in convex MINLP

    J. Blomqvist, E. Tamm, J. Kronqvist, A. Lundell

    Optimization Online

  2. 2026

    Separating hyperplanes for mixed-integer polynomial optimization problems

    C. Eggen, J. Kronqvist, A. Lundell, S. Volkwein

    Optimization Online

Global optimization

Reformulations and global optimization

Earlier research by the team on global optimization of nonconvex MINLP problems, in particular signomial transformations and reformulations, which also underlies SHOT’s reformulation engine.

  1. 2018

    Solving global optimization problems using reformulations and signomial transformations

    A. Lundell, T. Westerlund

    Computers & Chemical Engineering, 116, 122–134

    doi:10.1016/j.compchemeng.2017.10.035

  2. 2016

    Global optimisation of a portfolio adjustment problem under credibility measures

    A. Lundell, K.-M. Björk

    International Journal of Operational Research, 25(4), 464–474

    doi:10.1504/ijor.2016.075292

  3. 2015

    Representation of the convex envelope of bilinear terms in a reformulation framework for global optimization

    A. Lundell, T. Westerlund

    Computer Aided Chemical Engineering, 37, 833–838

    doi:10.1016/b978-0-444-63578-5.50134-1

  4. 2013

    A reformulation framework for global optimization

    A. Lundell, A. Skjäl, T. Westerlund

    Journal of Global Optimization, 57(1), 115–141

    doi:10.1007/s10898-012-9877-4

  5. 2013

    Refinement strategies for piecewise linear functions utilized by reformulation-based techniques for global optimization

    A. Lundell, T. Westerlund

    Computer Aided Chemical Engineering, 32, 529–534

    doi:10.1016/b978-0-444-63234-0.50089-0

  6. 2013

    The reformulation-based αGO algorithm for solving nonconvex MINLP problems – some improvements

    A. Lundell, T. Westerlund

    Chemical Engineering Transactions, 32, 1321–1326

  7. 2013

    Improved discrete reformulations for the quadratic assignment problem

    A. Nyberg, T. Westerlund, A. Lundell

    Lecture Notes in Computer Science, 7874, 193–203

  8. 2012

    Finding an optimized set of transformations for convexifying nonconvex MINLP problems

    A. Lundell, T. Westerlund

    Computer Aided Chemical Engineering, 31, 1497–1501

    doi:10.1016/b978-0-444-59506-5.50130-9

  9. 2011

    Global optimization of mixed-integer signomial programming problems

    A. Lundell, T. Westerlund

    Mixed Integer Nonlinear Programming, The IMA Volumes in Mathematics and its Applications, 154, 349–369

    doi:10.1007/978-1-4614-1927-3_12

  10. 2011

    Some notes on convex relaxations

    T. Westerlund, A. Lundell, J. Westerlund

    AIDIC Conference Series, 10, 383–392

  11. 2011

    Global optimization with C2 constraints by convex reformulations

    A. Skjäl, A. Lundell, T. Westerlund

    Chemical Engineering Transactions, 24, 373–378

  12. 2011

    On convex relaxations in nonconvex optimization

    T. Westerlund, A. Lundell, J. Westerlund

    Chemical Engineering Transactions, 24, 331–336

  13. 2010

    Global optimization of signomial programming problems

    T. Westerlund, A. Lundell

    Workshop on Mixed Integer Nonlinear Programming

  14. 2009

    Convex underestimation strategies for signomial functions

    A. Lundell, T. Westerlund

    Optimization Methods & Software, 24(4–5), 505–522

    doi:10.1080/10556780802702278

  15. 2009

    Some transformation techniques with applications in global optimization

    A. Lundell, J. Westerlund, T. Westerlund

    Journal of Global Optimization, 43(2–3), 391–405

    doi:10.1007/s10898-007-9223-4

  16. 2009

    Implementation of a convexification technique for signomial functions

    A. Lundell, T. Westerlund

    Computer Aided Chemical Engineering, 26, 579–583

    doi:10.1016/s1570-7946(09)70097-5

  17. 2009

    Optimization of transformations for convex relaxations of MINLP problems containing signomial functions

    A. Lundell, T. Westerlund

    Computer Aided Chemical Engineering, 27, 231–236

    doi:10.1016/s1570-7946(09)70259-7

  18. 2009

    On the relationship between power and exponential transformations for positive signomial functions

    A. Lundell, T. Westerlund

    Chemical Engineering Transactions, 17, 1287–1292

  19. 2009

    On the relationship between some transformations for positive signomial terms

    A. Lundell, T. Westerlund

    AIDIC Conference Series, 9, 187–196

  20. 2009

    Transformation techniques for signomial functions in global optimization

    A. Lundell

    PhD thesis, Åbo Akademi University

  21. 2008

    Exponential and power transformations for convexifying signomial terms in MINLP problems

    A. Lundell, T. Westerlund

    Proceedings of the 27th IASTED International Conference on Modelling, Identification and Control, 154–159

  22. 2007

    Optimization of power transformations in global optimization

    A. Lundell, T. Westerlund

    Chemical Engineering Transactions, 11, 95–100

Benchmarks

Solver comparisons

A comparison of SHOT with other convex MINLP solvers on the convex instances in MINLPLib. Note that the paper is from 2019 and used an older version of SHOT (0.9.2); SHOT has changed considerably since.

  1. 2019

    A review and comparison of solvers for convex MINLP

    J. Kronqvist, D. E. Bernal, A. Lundell, I. E. Grossmann

    Optimization and Engineering, 20(2), 397–455

    doi:10.1007/s11081-018-9411-8 Open access

Benchmark files and results    Mittelmann's MINLP benchmarks

Theses

Theses on SHOT

Master’s theses at Åbo Akademi University that have contributed to SHOT.

  1. 2025

    Developing a Python interface utilizing pybind11 for SHOT

    Johan Ekman

    Master’s thesis, Åbo Akademi University

    Contribution: The initial Python interface

  2. 2025

    Enhancements for nonconvex MINLP in SHOT

    Joakim Blomqvist

    Master’s thesis, Åbo Akademi University

    Contribution: Nonconvex MINLP

  3. 2024

    Automated release management and testing for SHOT

    Maxemilian Grönblom

    Master’s thesis, Åbo Akademi University

    Contribution: Release management and testing with GitHub

  4. 2024

    Implementation of a distributed benchmarking system for optimization solvers

    Filip Westersund

    Master’s thesis, Åbo Akademi University

    Contribution: The benchmark system

  5. 2023

    Implementation of an application for analyzing and visualizing benchmark results for optimization solvers

    Oscar Härtull

    Master’s thesis, Åbo Akademi University

    Contribution: VIVA, for analyzing and visualizing benchmark results