Tias Guns

Modeling and Explaining an Industrial Workforce Allocation Problem (Extended Abstract)

We present an industrial case on workforce allocation and scheduling in the aircraft manufacturing industry, where available teams need to be assigned to logistical operations. This application presents several challenges, such as the scale of the problem, the need for fair workload distribution, and the need for metho...

Predictive Dual Smoothing for Column Generation

P predictive dual smoothing is introduced, which instead combines the current dual solution with a learned prediction of future duals to steer pricing towards variables that are more useful in subsequent iterations.

Unified Programmatic Access to CO Benchmarks, to Connect Constraint Solving Communities (Tool Paper)

This work proposes a programmatic abstraction for CO benchmark sets that facilitates cross-community access to benchmarks and systematic comparisons of solvers across paradigms, and implements file writers to multiple solver-oriented formats.

Towards Step-Wise Explanations of Large Search Trees (Short Paper)

Translating finite-domain integer constraint models to CP/SMT/ILP/PB/SAT solvers with CPMpy

The goal is to translate high-level constraint satisfaction and optimization problems into any lower-level formalism, including CP, SMT QF-LIA, ILP, PB and (Max)SAT, and to present a modular framework for transforming the high-level modeling language to CP/SMT/ILP/PB and (Max)SAT solvers.

Efficient Reformulations of Half-reified Global Constraints using Auxiliary Variables

A set of reformulation rules are proposed that allow the use of half-reification of a global constraint with any CP solver that supports the “normal” global constraint propagator, and expand the range of available solvers and constraint models that can be used in XCP techniques or for solving CSPs with compound constra...

LLM-Guided Evolutionary Search for Constraint Model Reformulation to Improve Solver Efficiency

Combinatorial problems appear in numerous industrial applications. A common approach is to formulate these problems as declarative constraint models that can subsequently be compiled to and solved by a range of back-end solvers. Recent work shows that Large Language Models (LLMs) can produce correct models from natural...