Wow, cool! The model is specified as a constrained nonlinear optimization problem for which a solution is found using high-quality proprietary numerical solvers.[a] All partial differential equations specifying the model have a basis in economic theory or in heuristics and approximations shown to be consistent with reality. Parameters come directly from (what I assume is a large amount of) economic data collected by the Danish government.

The authors working for the Danish government deserve an A+ for making their code and assumptions public, along with comprehensive high-quality documentation.[b] It was a delightful surprise to click on the link and find... a carefully curated repo.

I have only one nitpicking: This looks like the kind of project that should have been -- and in fact probably should be -- implemented in Julia, instead of in a proprietary language. I suspect many heuristics and approximations could be more accurately modeled by ML components, interspersed between equations, as has long been proposed by Julia folks like Chris Rackauckas.

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[a] https://news.ycombinator.com/item?id=30028188

[b] https://media.githubusercontent.com/media/DREAM-DK/MAKRO/mai...