Scipy successfully included Agner Fog’s C++ code for the Wallenius and Non-central Hypergeometric distributions by requesting that Agner Fog relicense the code for BSD. The correspondence is in Scipy’s repo at https://github.com/scipy/scipy/blob/909baa6b21a884afa8f8e1f8f3226fa9e55bc2ad/scipy/stats/biasedurn/license.txt#L10.
The question being, can we now include this code in our repo or do we need to get explicit permission from Agner Fog too? The zip file he mentions contains a license.txt but is still under GPL. Does the fact that Scipy is BSD-3 allow us to include and/or modify the code for usage in Stan-math?