Mixed Integer Programming Workshop 2024

Slides for #EuroMIP25 are online!

Thanks a lot for posting this coverage of the #EuroMIP25 workshop. This is a great service for all who cannot participate in inaccessible conferences but still want to feel connected to the MIP community.

And that's a wrap on #EuroMIP25! Three packed days of great talks and inspiring research.

Huge thanks to @sophie.huiberts.me , @matbesancon.bsky.social, the rest of the MIP committee and the local team for making this first edition a real success!

Lucas Létocart’s wraps up with a dive into Decomposition Methods for Quadratic Programming problems, both convex and non-convex.

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A resounding success for the first #EuroMIP25, strong interest from participants to learn from each other on the whole spectrum of MIP research, all very strong signals that the community is in demand for the format and topic!

Stefan Kuhlmann’s talk focused on Sparse Integer Solutions and Approximations. This is an important topic both theoretically and in applications where nonzero entries can represent costly decisions or changes.

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Sophie Demassey @sofdem.bsky.social kicks off the third and final day of #EuroMIP25 with a talk on Block Coordination of Nonlinear Network and Discrete Optimization. She focuses on scheduling nonlinear flow networks, with an application to load shifting in drinking water systems.

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group picture of the workshop participants. its a crowd, 60 to 80 people i think

That's it for this #EuroMIP25. Thanks everyone for making this workshop a success

François Lamothe explores strengthening linear relaxations for MIPs by combining Dantzig-Wolfe and Fenchel decompositions.

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Laurent then dives into some implementation choices and defines the concepts of primal and dual superbasics. The overall trade-off promotes both speed and numerical stability.

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Yelena Yuditsky presents recent advances on solving special classes of integer programs with bounded subdeterminants.

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Johannes Thurauf presents joint work with Martin Schmidt on an Exact Method for Nonlinear Network Flow Interdiction Problems, modeled as max–min bilevel programs with nonconvex, nonlinear flow constraints on the follower side.

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Leona Gottwald talks about which components are truly necessary for delivering good performance in modern MIP solvers, drawing from her development experience of HiGHS (and others).

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Fabio Furini talks about Hidden Bilevel Structures in Graph Disconnection Problems, focusing on the capacitated vertex separator and the k-vertex cut. Both are reformulated as Stackelberg games: a leader deletes vertices and a follower optimizes over the disconnected graph.

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The talk ends with an example on the Hamming cube, where one of the parameters corresponds to counting return walks to the origin, followed by a few open questions on tightening bounds and extending the current framework.

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Monique Laurent opens the second day of #EuroMIP25 with a presentation on Semidefinite approximations for bicliques and biindependent pairs. The focus is on measures involving the size and balance of independent sets in bipartite graphs such as their sum or product.

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Second day of #EuroMIP25 starting with Monique Laurent speaking about biindependent sets in graphs and SDP, with a hybrid board+slides format!

Frédéric Didier presents the MIP-related aspects of Google’s CP-SAT solver, with a focus on how linear relaxations, cuts, and presolve are integrated into a framework originally designed for pure integer problems.

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Results show tight gaps (often under 3%) and the ability to process much larger instances. Solving the anticlustering step exactly remains work in progress. #EuroMIP25 #orms

Meike Neuwohner presents a characterization of total unimodularity for disjoint hypergraphs, , i.e. hypergraphs whose hyperedges of size at least four are pairwise disjoint.

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Implemented in the GCG solver, the approach shows strong improvements, particularly on instances with large root gaps. Rönnberg concludes with potential research directions, specifically on optimality conditions and the pricing subproblem. #EuroMIP25

Marouane is live tweeting all #EuroMIP25 talks, follow him to stay up to date

Across all cases, Lassota highlights how careful structural analysis opens pathways to tackle IPs more effectively when key problem structures are exploited. #EuroMIP25

Johannes Thürauf presents work on robust network design for systems with nonconvex flows taking into account demand uncertainties. The goal is to ensure feasible operation under all load scenarios within a defined uncertainty set, where injections and withdrawals vary freely.

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Nadia Brauner opens the #EuroMIP25 workshop with a talk on the need to integrate environmental and societal issues into Operations Research. She argues that optimization must go beyond cost and efficiency to reflect real-world consequences. Two examples illustrate this:

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Alex with her slide. She has drawn cartoon pictures of various types of shapes and structures for the constraint matrix, along with the relevant parameters for which MIP is FPT

Alex Lassota is speaking about FPT algorithms for MIP with these awesome fun and clear slides #EuroMIP25

Johannes stands in front of a slide with figures and formulas. The title of the slide is "how many scenarios do we need"

The second session dives into technical work. Johannes Thürauf speaks on applications to robust adjustable network design with both theoretical and computational work #EuroMIP25

Nadia standing in front of a whiteboard. She is a white woman with short greying hair. The text on the slide reads "Take a step back from decision-support tools As technical experts and analysts, OR practitioners are well placed to understand the limits, costs and possible effects of decision-support tools • Operations research as a profession, Churchman, 1970 • The social responsibility of operational research, Ackoff, 1974 With Odile Bellenguez and Alexis T soukias • Is there an ethical operational research practice? And what this implies for our research? 2023 • From decision aiding to the massive use of algorithms. where does the responsibility stand? 2024 • Teaching ethical, societal and environmental challenges of algorithms through a case study 2025 (in French) also with Christine Solnon"

Nadia Brauner gave an inspiring lecture where she spoke about OR researchers ethical responsibilities, in context of two programs she worked on in her local area #EuroMIP25

I'm proud to host the first European MIP Workshop today. 17 exciting talks about all aspects of mixed integer programming #EuroMIP25