Gurobi licenses

[jon-wurtz]

We use Gurobi for some of our decoders:

bloqade-decoders/pyproject.toml

Line 27 in 807b5da

"gurobipy>=13.0.1",

but Gurobi has different licenses for academics vs. enterprise. Can we check that using this tool does not accidentally run afoul of license restrictions?

[Whatsonyourmind]

The MLE decode is a standard binary MIP — minimize Σ w_i·e_i with weights w_i = log((1−p_i)/p_i), subject to the syndrome parity constraints H·e ≡ s (mod 2), which you linearize with integer slacks (H·e = s + 2k, k ≥ 0). Nothing in that formulation is Gurobi-specific, so the cleanest way to sidestep the license question entirely is to add an open-solver backend alongside GurobiDecoder. HiGHS (via highspy, fully open, no license server and no academic/enterprise distinction) handles binary MIP and slots into the same model; CBC through PuLP/python-mip is the other option. It mirrors what you already do with the Tesseract/Table/MWPF decoders — just another backend.

The honest tradeoff: Gurobi is usually faster on the hard instances, so for large-distance codes you may see longer solve times. But you remove the ~2k-constraint ceiling of the bundled gurobipy size-limited license and the academic-vs-enterprise ambiguity altogether, which sounds like the actual concern here.