[Election-Methods] Unnecessary voting method? (was SPPA - support building engine)

[Steve Eppley]

Hi,

It was not that I didn't read the rest of Stephane's earlier message.  
It was his lack of clarity: His next example looked like he switched to 
a different voting method, because his description of the tallying was 
very different and he did not indicate he was using the same method 
("Repetitive Condorcet (Ranked Pairs (Winning Votes)) Elimination.").

At this point, I will assume Stephane does not intend to provide a 
definition of that voting method nor a link to it, and I don't have time 
to hunt in older messages to see if it was defined once upon a time. 

Regards,
Steve
-------------
Stéphane Rouillon wrote:
> My advice to Steve is to read all an email before comments.
> Cut-off were applied further building the counter-example in the part 
> he snipped...
> Of course without cut-off, the original ordering method comes back.
>
> "meaningless winners which could not get elected with SPPA in the end."
>
> refers to the fact that the multiple-winner method will not 
> necessarily elect a candidate that received the most support
> in a district. Again, it is a matter of considering an election as a 
> representative exercise and not as a battle.
>
> Stéphane Rouillon
>
> Steve Eppley a écrit :
>> Hi,
>>
>> Stéphane's latest example (immediately below) is very different from 
>> his earlier example that I quoted (further below) which he tallied 
>> using a voting method he called "Repetitive Condorcet (Ranked Pairs 
>> (Winning Votes)) Elimination."  His earlier example had no "approval 
>> cutoffs" and his latest example appears to have no connection to 
>> Ranked Pairs or Condorcet.  Thus he hasn't provided a basis for 
>> claiming my comment was wrong.
>>
>> My advice to Stéphane for when he sobers up (just joking) is to 
>> reread his earlier example and then provide a clear definition of the 
>> "Repetitive Condorcet (Ranked Pairs (Winning Votes)) Elimination" 
>> method, or a link to its definition, so we will know what voting 
>> method he was writing about.  Based on the name he gave it and from 
>> his earlier example, it appears (to me, at least) to be the method 
>> that iteratively eliminates the candidate ranked last by MAM until 
>> one remains.
>>
>> The thrust of my comment was that since MAM satisfies Peyton Young's 
>> LIIA criterion, it follows that MAM elects the same candidate as the 
>> more complex voting method that iteratively eliminates the candidate 
>> ranked last by MAM until one candidate remains.  Was Stéphane 
>> claiming this is wrong, when he wrote that my comment was wrong?
>>
>> Second, I do not understand what he meant where he wrote, 
>> "meaningless winners which could not get elected with SPPA in the 
>> end."  I suspect it is not relevant to the comment I made.
>>
>> --Steve
>> ---------------------------------
>> Stéphane Rouillon wrote:
>>  
>>> First Steve's comment is wrong as shown below: A > B > C.
>>>    
>>>> 33: A > B | C
>>>> 31: B > C | A
>>>> 33: C | A > B
>>>> 3:   B | A > C
>>>>
>>>> C is eliminated with 33 votes as support.
>>>> B is eliminated with 34 votes as support.
>>>> A is last eliminated but receives no rallying voters and finishes 
>>>> with 33
>>>> votes as support.
>>>>   B wins.
>>>>       
>>> Second, as written before, scores or supports matter, not 
>>> meaningless winners which could not get elected with SPPA in the end...
>>>
>>> S.Rouillon
>>>
>>> Steve Eppley a écrit :
>>>    
>>>> Hi,
>>>>
>>>> Assuming I'm correctly understanding a voting method Stéphane 
>>>> Rouillon used in a recent message (excerpted below), which he 
>>>> called "Repetitive Condorcet (Ranked Pairs(Winning Votes)) 
>>>> elimination," it is unnecessarily complicated because it chooses 
>>>> the same winner as Ranked Pairs(Winning Votes), which of course is 
>>>> simpler.
>>>> Ranked Pairs(Winning Votes), also known as MAM, satisfies H Peyton 
>>>> Young's criterion Local Independence of Irrelevant Alternatives 
>>>> (LIIA).  One implication of LIIA is that elimination of the 
>>>> last-ranked candidate(s) does not change the ranking of the 
>>>> remaining candidates.
>>>>
>>>> By the way, a different criterion has been masquerading as LIIA in 
>>>> Wikipedia.  Peyton Young defined the real LIIA in his 1994 book 
>>>> Equity In Theory And Practice (if not earlier).
>>>>
>>>> --Steve
>>>> --------------------------------------
>>>> Stéphane Rouillon wrote:
>>>> -snip-
>>>>  
>>>>      
>>>>> Let's try a counter-example:
>>>>>
>>>>> 3 candidates A, B, C and 100 voters.
>>>>> Ballots:
>>>>> 35: A > B > C
>>>>> 33: B > C > A
>>>>> 32: C > A > B
>>>>>
>>>>> Repetitive Condorcet (Ranked Pairs(winning votes)  ) elimination 
>>>>> would produce
>>>>>
>>>>> at round 1:
>>>>> 68: B > C
>>>>> 67: A > B
>>>>> Thus ranking A > B > C
>>>>> C is eliminated.
>>>>>
>>>>> at round 2:
>>>>> 67: A > B is the ranking
>>>>> B is eliminated
>>>>>
>>>>> at round 3:
>>>>> A wins.
>>>>>             
>>>> -snip-
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>>>>       
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>>
>>   
>
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