Re: Twenty Bank Robbers -- solution (?)

At 01:13 PM 7/25/96 -0500, Igor Chudov wrote:
Igor Chudov wrote:
Here's a puzzle for our game theorists.
I forgot to say what the GOALS are. The goals of every individual cypherpunk are (in from highest to lowest priority):
1. Stay alive 2. Get as much money as possible 3. Keep as many cypherpunks alive as possible, all other things being equal.
The first cypherpunk should propose a 10-way split: #s 11-20. It's the best offer #s 10-18 will be assured of getting without having to kill anyone. Once any one dies, I think the results will always boil down to #19 getting 100% of the money (when #s 1-18 are dead, #19 proposes that #19 gets 100% of the money and his vote is 50%, so he "wins". #20 kills him out of spite and takes it all anyway, though. No honor amongst thieves.) John -- J. Deters "Captain's log, stardate 25970-point-5. I am nailed to the hull." +-------------------------------------------------------+ | NET: jad@dsddhc.com (work) jad@pclink.com (home) | | PSTN: 1 612 375 3116 (work) 1 612 894 8507 (home) | | ICBM: 44^58'33"N by 93^16'42"W Elev. ~=290m (work) | | PGP Key ID: 768 / 15FFA875 | +-------------------------------------------------------+

At 17:32 -0500 7/25/96, John Deters wrote:
At 01:13 PM 7/25/96 -0500, Igor Chudov wrote:
Igor Chudov wrote:
Here's a puzzle for our game theorists.
I forgot to say what the GOALS are. The goals of every individual cypherpunk are (in from highest to lowest priority):
1. Stay alive 2. Get as much money as possible 3. Keep as many cypherpunks alive as possible, all other things being equal.
The first cypherpunk should propose a 10-way split: #s 11-20. It's the best offer #s 10-18 will be assured of getting without having to kill anyone. Once any one dies, I think the results will always boil down to #19 getting 100% of the money (when #s 1-18 are dead, #19 proposes that #19 gets 100% of the money and his vote is 50%, so he "wins". #20 kills him out of spite and takes it all anyway, though. No honor amongst thieves.)
As I noted in a separate message, I think that if the killing starts it will not necessarily go as far as you propose. Since, when it is #17's change, all he needs is one extra vote, he can offer to split with #20 (who, as you note, will get nothing from #19 - so it is in his interest to accept any offer from #17 that is for at least 50% [anything less he should/could reject since #18 will/should offer him at least 50% to prevent #18 getting killed]). Also, I question WHO #1 should offer the split to. All he wants is 9 extra votes so it does not need to be #11-20. I'd think that #1-10 (if #1 wants part of the money) or #2-11 (if he does not but wants to hedge his bet by allowing for one "No" vote from that group) would be better since by voting "YES", each gets to not need to worry about coming up with a split or risking death (11-20 do not have this type of immediate threat hanging over their heads so they are more likely to vote "NO" and hope for a better deal [as the first ones start dropping dead, there are less votes needed so the "I'll Bribe you with part of the Split" offers are going to be worth more to those who are included]).
participants (2)
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John Deters
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Robert A. Rosenberg