It is possible! But with more than two dimensions, you have to allow deviations from perfect proportionality to guarantee a solution exists. The more dimensions

It is possible! But with more than two dimensions, you have to allow deviations from perfect proportionality to guarantee a solution exists. The more dimensions, the worse it gets, until eventually proportionality breaks down entirely. [1] defines a method to do this and simulates the results on an election where district and party seats are distributed proportionally and divvied up by gender proportionally. The result is a better national proportionality at the expense of worse local proportionality. [1]: https://www.pnas.org/doi/10.1073/pnas.2109305119 https://www.pnas.org/doi/10.1073/pnas.2109305119