matrix_permanent https://codegolf.stackexchange.com/questions/97060/calculate-the-permanent-as-quickly-as-possible https://github.com/XanaduAI/thewalrus/blob/master/thewalrus/_permanent.py ( https://doi.org/10.1016/j.jcp.2022.110990 , http://abel.math.umu.se/~klasm/prog/PERM/ )