[EM] Re: majority rule, mutinous pirates, and voter strategy

[Juho Laatu]

Hello James,

You wondered how familiar I am with different strategies etc. I have  
studied the voting methods for quite some time and I have visited also  
Blake Cretney's web site. I think I know most of the basic stuff but  
unfortunately have not had time to follow all the details of the  
discussions on this mailing list, so I don't master all of the  
abbreviations of three and four letters.

On Mar 17, 2005, at 12:59, James Green-Armytage wrote:

> 	Have you read my 3/14 post yet?
> http://lists.electorama.com/pipermail/election-methods-electorama.com/ 
> 2005-March/015125.html

I'm off-line at the moment so I can't check. I guess yes but if I  
haven't, I'll do that.

> I suppose we
> could try to take ranked ballots from a STV elections and see what  
> sort of
> strategic possibilities would have existed if it had been a Condorcet
> election instead.

Yes, that would be a good check against real life data. I'd be  
interested in doing the tests (at least in theory) so that before  
opening the ballot files we would read the local newspapers from the  
time before the elections and then make strategy recommendations to  
different type of voters. It is important that the strategies would be  
applied before knowing the actual outcome of the election and the  
ballots. This method would help seeing which strategies can be applied  
in real life an which not.

> 	It's far better to err on the side of caution, especially when the
> integrity of the electoral process and the credibility of pairwise  
> count
> methods are at stake.

I agree that risk analysis must be done and serious risks must be  
eliminated (if possible) by selecting appropriate voting methods.

> 	I have provided several made-up examples along these lines. If you  
> want
> real examples, you have to wait for the method to be adopted for
> contentious elections.

Made-up examples are fine with me. What I often would like to see more  
is to make the voters less clairvoyant and limit their information  
better to what they are likely to have available in a real voting  
situation. It is thus not enough if some voting result could have been  
manipulated by appropriate strategical voting. The strategy must be  
usable also in real life to be a real threat.

>> One example strategy that I find interesting (because it is not so  
>> easy
>> to ignore) is one where voters try to create a loop that includes only
>> the candidates of a competing party. All voters add at the end of  
>> their
>> ballot a list of candidates of the competing party in certain order.  
>> Do
>> we need to defend against this?
>
> 	Yes, among other forms of the burying strategy.

I'm particularly interested in strategies that can be implemented  
without any prior knowledge of the expected outcome of the election.  
That's why I picked this strategy. This category of strategies is  
dangerous in the sense that it makes my target/hope of keeping the  
voting methods close to the best sincere methods harder to achieve.

> 	To begin with, the method should be Smith-efficient. That way, if  
> none of
> the strategizers' party's (party B's) candidates actually beat the  
> other
> party's (party A's) candidates, the winner will come from party A. With
> minimax, party A could be a party of clones with a mutual majority, and
> still fall victim to party B's strategy.

Let's say that because of the applied strategies both A and B  
candidates have a loop within the party. If party B is a bit smaller  
than party A, then the loop within party A must be weaker than the loop  
within party B. In this case there would be no need for a defence (=>  
also basic MinMax would be fine).

I'm worried about the possibility that all voters would have to apply  
strategies in their ballots or otherwise they would lose the election.  
A voting method that forces people to follow complex unintuitive  
strategies surely is not a good voting method. If only party B applies  
the strategy, then party A could lose the election if basic MinMax was  
used.

I have sometimes played with the idea that if there are rules that try  
to eliminate party internal loops, maybe those rules should apply to  
parties only and not to other, maybe sincere loops. One could solve  
this by using a method that takes into account which candidates have  
been declared as belonging to the same party. Loops among them would  
not be used against them. I don't know if such methods have already  
been discussed somewhere. I haven't analysed these well enough to have  
any firm opinon. And I understand that there are also malicious burying  
loops between that involve several parties.

One big weakness of the loop voting strategy is that one has to agree  
how to construct the loop. Is it ABCDA or is it ADCBA or something  
else. Also voters have to be quite educated to understand that they  
should pick a random starting point of the loop and create the loop  
based on this information. In large public elections these problems may  
be enough to make the strategy useless and defensive methods  
unnecessary.

> 	Second, the method should at least be a wv method, if not something
> stronger (cardinal pairwise, AWP, CWO, AERLO/ATLO, etc.). I've explored
> this idea in other places, and will continue to do so...

I can't comment since I can not estimate the risks and need for defence  
yet.

> 	There are better ways to curtail strategy; reducing preference spaces  
> is
> not necessary.

I agree that reducing preference spaces is quite violent. On the other  
hand in practical elections sometimes simple ballots are a benefit. But  
maybe it is also simple enough to write a ranking number next to each  
candidate.

Best Regards,
Juho