- We've added support for Gurobi and HiGHS. 
- The implementation is a simple prototype, which we will use as our starting 
point. 
- We ran some experiments comparing Gurobi, HiGHS, CPLEX, and Soplex on the 
default optimal benchmark suite. 
- A branch with the prototype is here:  
https://github.com/remochristen/downward/tree/lpsolvers_hack

We have some initial results to share, which can be found here:

https://ai.dmi.unibas.ch/_experiments/gustavo/sprint2026_lpsolvers/data/sprint20
26_lpsolvers-benchmark_solvers-eval/sprint2026_lpsolvers-
benchmark_solvers.html#summary

A complete description of the experimental setup and an analysis of the results 
are in the attached file.

We want to explore LP solvers, such as Gurobi, HiGHS, Google OR-Tools, and FICO 
Xpress. So far, we have implemented interfaces for Gurobi and HiGHS. The 
implementations currently use some 'hacks' to change two-sided constraints into 
one-sided versions during model creation. As one of the next steps, we want to 
change the LP interface to only support one-sided constraints.