[EM] Single Winner Systems categorization

[Tom Ruen]

Below is my proposed categorization for the Wikipedia "Election system" page
listing single winner systems.
http://en.wikipedia.org/wiki/Voting_system#Single_Winner_Systems

My biggest change (from the current page) reclassifies "Yes/No Voting" into
"One Choice voting", and moved Approval to the "Rated Value Voting"
category.


I hope my "One Choice Vote" category will be recognizes as unique, even if
it doesn't offer all the fun games of more advanced methods.

I also removed the "tied-ranking" subcategory for Ranked Choice since I
don't believe it is well defined which methods can allow tied rank ballots,
and it may be equally undefined how such ballots will be counted.

Instead I added a subcategory "Sequential rounds" to connect methods that
have sequential counting.

I was unsure about MCA under "Ratings" since it has no article written about
it, but put it in a "Multiple round" category based on a one-line
description.

Comments or suggestions are welcome.

Sincerely,
Tom Ruen

P.S. I added a quick listing for those (nonparty vote) at the end under (B),
but I'm less satisfied there, and I prefer "Majority/plurality" versus
"SemiPR" versus "PR" as the broad categories.

***********************
(A) Single Winner Systems

Single Winner systems can be classified by how a vote is cast:

    1 '''One Choice Voting''' A valid vote offers a single most supported
candidate.
    2 '''Ranked choice Voting''' A valid vote can rank candidates 1,2,3...
(Tied rankings may permitted in some methods)
    3 '''Rated Value Voting''' A valid vote allows numerical
values/categories to be associated with each candidate. Every candidate can
be scored independent of the competition. (The set of valid
values/categories is limited.)

They can also be classified on how many times votes can be counted. Methods
like Plurality, Borda, and Approval with single counting rounds are simpler
since voters can be sure to know how their votes will be applied.

1. One Choice Voting methods
    FPTP
    Sequential rounds
        Runoff voting
        Elimination runoff
        Exhaustive runoff
    Random ballot

2. Ranked Choice Voting methods
    Borda count
    Sequential rounds
        Instant Runoff Voting/Alternative Vote/Preference voting (IRV)
            Supplementary Vote - reduced IRV process (2 rankings, 2 rounds)
        Coombs' method
        Bucklin voting
    Condorcet method (Parallel pairwise rounds)
        Ranked Pairs
        Cloneproof Schwartz Sequential Dropping (CSSD)
        Copeland's method
        Ranked Majority Defeat Disqualification (DMDD)

3. Rated Value Voting methods
    Approval voting
    Cardinal Ratings (CR)
    Multiple rounds:
        Majority Choice Approval (MCA)
.............................

QUICKLY CONSIDERED MULTIPLE WINNER METHODS

(B) Multiple Winner elections (not party-list)
    One Vote per Winner (W votes)
        Bloc voting/Plurality-at-large
    Less than One Vote per Winner (<W votes)
        Limited Voting (LV)
    One Single Vote (1 vote)
        Single Nontransferable Vote (SNTV)
    One Distributed Vote (1 vote manually split among candididates)
        Cumulative Voting (CV)
        Equal&Even Cumulative Voting (E&E CV) - vote for N candidates, each
gets 1/N votes.
    Ranked Choice Voting (1 vote automatically split among candidates using
rank ballot)
        Single Transferable Vote (STV)