[EM] Participation Criteria and Bucklin - perhaps they *can* work together after all?

Chris Benham cbenhamau at yahoo.com.au
Mon Jun 17 13:58:14 PDT 2013


The criterion ("criteria" is the plural) you suggest is not new. It is called Mono-add-Top, and comes from Douglas Woodall.

It is met by IRV and MinMax(Margins) but is failed by Bucklin. In my opinion IRV is the best of the methods that meet it.
26: A>Y>X
25: B>Y>X
17: C>D>X
17: E>F>X
17: G>H>X
The majority threshold is 51 and X wins in the third round. But if we add anywhere between 3 and 100 
X>Y ballots then Y wins in the second round.
You'll find some interesting stuff on Kevin Venzke's old page:
Notice that your version (in an earlier post) of the Plurality criterion is wrong.
Chris Benham
Benjamin Grant wrote (17 June 2013):
OK, let's assume that as defined, Bucklin fails Participation. 

Let me specify a new criteria, which already either has its own name that I do not know, or which I can call Prime Participation:

"Adding one or more ballots that vote X as a highest preference should never
change the winner from X to Y"

In other words, expressing a first place/greatest magnitude preference for
X, if X was already winning, cannot make X not win.

This may be another one so basic that few or maybe no real voting systems
fail it?

-Benn Grant

eFix Computer Consulting

<mailto:benn at 4efix.com> benn at 4efix.com

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