[EM] STV and single constraints, like gender quotas

[Peter Zbornik]

Dear all,

do anyone of you know the best way to incorporate single constraints
into STV and proportional rankings from STV (see for instance:
http://www.votingmatters.org.uk/issue9/p5.htm)?
For instance, the constraint can be that at least 1/3 of the elected
seats go to candidates of each gender.
I found some information in the links below, but I wonder if there are
better or more recent suggestions:
http://www.votingmatters.org.uk/ISSUE9/P1.HTM
http://www.votingmatters.org.uk/issue9/p5.htm

Best regards
Peter Zborník