[EM] Monotonic Proportional Representation System?

Stephane Rouillon stephane.rouillon at sympatico.ca
Tue Apr 22 14:24:07 PDT 2003

Replace the IRV inner motor by a Condorcet method in SPPA:
(4th post is in english)
It should do the job. I hope you like it....

Clinton Mead a écrit :

> Is there a monotonic proportional representation system, one that allows
> voters to express their preferences based on individual options, not
> parties or something similar? That is, a system proportional
> representation system that matches these criteria at all times. (Except
> for maybe extreme cases, where there are more options than voters, for
> example).
> (1) If option A is selected, then ranking option A higher on one vote
> without changing the order of other preferences must not cause A to
> lose. (Monotonicity).
> (2) If there is a set of options X, and N votes who rank options in X
> below only non-selected options and options in X, and N is greater than
> the K * quota, than at least K options in X shall be selected, or all
> options in X. (For example, if 5 votes are A,B,C,D and 6 votes are
> B,A,C,D, and the quota is 8, this criteria dictates that A or B is
> selected).
> So far I've only found Single Transferable Vote as a individual option
> based proportional representation system, and STV is not monotonic, as
> it eliminates candidates in a similar fashion to IRV, which itself is
> not monotonic.
> I was thinking about a possible monotonic proportional representation
> system loosely based on condorcet, but I'm not sure if one even exists
> or if its possible.
> Thanks.
> Clinton.
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