Added: 4 years ago
From: anuzis
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  • We're learning this in Microeconomics. What other classes is this used for?

  • @pr1nyc1 political science

  • "jane is thinking, if I move us to this column, I get one years less.

    jane also gets a knife in the neck when I get out in eight years.

  • "Jane always finds that left column attractive" until she realizes living 5 years in prison known as a snitch (and people WILL find out, trust me) is hell, and decides, "nah, two years not being known as a rat is better" same goes for bob.

    the cops always say your friend confessed and you may as do so too, you'll be better off. if our players realize this is a trick, it won't work. you don't make their job easier by giving them evidence. they say you did something, make 'em prove it

  • love you man, look forward to more vids!!!!

  • Comment removed

  • thnx so much im working on a math fair project and this is my topic!! u answered all my questions

  • thanks for this video, you were awesome!

  • how does the game theory explain the situation in 70s when a soviet nuclear submarine was torpeed down by americans and the soviet well experienced general had order to strike back with everything they got including nucelear arsenal. but didnt he disabodiet refuse to order a retalitation . according to game theorist doesnt this make him a looser?

  • self policing!

  • enjoyed it to the max!!

  • helllll no, we're not stayin' in for 5 years. let's trick these suckers

  • Excellent job explaining!

  • @1WGUMCD0

    The most important thing to remember with game theory is that you need more than one 'player' hence you can't use game theory for most portfolio stuff, since game theory is about devising strategies dependent on other people's actions. Most situations involving more than one person where you are devising strategies based on actions can therefore be solved through game theory.

  • @1WGUMCD0

    Game theory isn't very applicable to financial markets, for that quantitative statistics and such are what you need. But game theory is definitely applicable in company strategy and tactics especially markets that are duopolies.

    I will send you some detailed links with examples if you are interested but basically it can be used for pricing tactics (bertrand competition), quantity competition (cournot competition), choosing levels of advertising, determining whether to enter markets.

  • @1WGUMCD0

    this is barely even game theory, it is like basic arithmetic is to maths. Game theory becomes much much more advanced than this when you move onto mixed strategy, bayesian games with imperfect information etc.

    Once you know advanced game theory you can apply it to many many situations.

    Games such as this barely scratch the surface.

  • man you did a great job...this was the kind of explanation I was looking for..........

    HATS off man!!!!!!!!!!1

  • Heheh, good explanation of it all.

  • This is the best explanation of game theories ever. I saw many of them posted by cool men, and could not get it. Thanx for showing what the columns mean :)

  • Great explanation but still one question remains; why are Bob and Jane in the same prison? Is this some weird co-ed Bangkok prison or is 'Jane' perhaps an effeminate nickname given by the other prisoners?

  • The tricky thing about game theory is that any time there is a benefit to an action, game theorist can use it, but human beings are not the rational calculating self interested beings imagined by Game Theory's designers. Humans are driven by a variety of factors, some live largely as base instinct driven animals, some live their lives for others, some seek only their own benefit in all things, and some are simply mentally ill... Like the paranoid schizophrenic who gave us Game Theory.

  • You explained this topic so simply THANK YOU!

  • Comment removed

  • But if Jane and Bob are friends would they be smart enough to know they should both stay quiet ?

  • @nsand91 that depends on wether or not they value friendship over freedom

  • The trouble with using this game to exemplify human nature is the coercion of the prisoners with the threat of jail time or the incentive of reduced jail time are unnatural externals. To break the game one simply has to imagine a society in which crime, jail, and jailers don't exist (all unnatural states of existence.)

  • thanks thanks thanks! I didnt get this at all until i watched your video! You explained it so simply!!

  • Different Prisoner's Dilemmas involve varying tariffs according to defaulting and staying quiet. With this template of 2/2, 8/1, and 5/5 years, it's DEFINITELY in your best interest to default

  • After watching three different videos I finally got it! Thanks Bob.

  • my brain hurts

  • ahh... Im so exausted because of all the studying, I cant absorb any information....

    I just wanna puch him in the face...

  • @8Julius8 Good luck on your exam.

  • One thing that this shows is the importance of trust. If it where you and your wife and you had a good relationship there wouldnt be a dilemma and both of you would get two years. We could do with a bit more trust in international relations...a system of rules that everyone stuck to would be to everyones advantage as we could get to some positive endpoints.

  • thanks

  • You kinda look like Sylar from Heroes. Thank you though. I got a final exam tmrw and I needed to review game theory a bit. Thanks

  • Hey i like your video, i want to know if you have any other about game theory bayesian equilibrium, nash equilibrium & sequential equilibrium exercises??

    Thanks

  • STONED!!!

  • sry i meant to say:

    i love HOW you say bob....BAAB

  • i love you say bob....BAAB

  • Excellent Job. I loved your explanation. Very clear.

  • hi

    I just wanted to say thanks for your video.

    Thanks to you I got a 8 on my paper for school. I think that is a B i'm not sure.

    Well thanks anyway.

  • hi,

    I just wanted to say thanks for this video.

    At first I did'nt understand a thing, but after watching it a couple of times I got it.

    I had to do a paper on prisoners dilemma and thanks to you I got a 8 for my paper. I think that is a B i'm not sure. But thanks any way.

    A grateful dutch girl.

  • Great video, I had trouble understanding this concept however you explained it very well. Thanks for keeping it simple.

  • lol you didn't have to tell the world that you didn't shower ^_^

    I laughed at your semi-slurred speech and rambling cause you're so sleepy.

    Great vid though... quite interesting.

  • Thank you very much. It was very clear to me, and helped me understand the Prisoner's Dilemma lecture that I had earlier today. Amazing that you can explain these things when you 'haven't woken up yet' !

  • Sooo, stay quiet :D

  • thanx

  • Thanks dude!

  • Thanks man.  Stay cool!

  • cool ending dude, loved it

  • I'm confused. How did you settle on the original punishments for Bob & Jane?....both prisoners ratting & they get 5, both staying quiet & they get 2. I can't imagine a court giving people a bigger sentence for ratting than staying quiet. Surely helping the police would buy you some grace. I can see what the game is about and I like the theory, its just those original figures I'm unsure about. Or am I missing the point, I'm not a mathematician. Yours, ConfusedUK

  • Hey Dave - fair question.

    Admittedly, the initial assumptions are artificial. The thought is that the courts don't have enough evidence to definitely know Bob & Jane are guilty so they can't give them a full prison sentence unless they admit to the crime.

    If both are quiet, the court can only do so much.

    If both rat out, the court gets harder evidence and can punish harder.

    If only one person rats out, that person gets favor from the court as you suggest, the other person bites the bullet.

  • @anuzis Don't forget that the punishment structure is set up in order for both to rat each other out.

  • @blamedaveLEEDS they have 5 years because they have proof against both. the reward by the court is the fact if one didnt rat on the other while the other did they would get 8 years instead of 5, so they still get 3 years less.

  • @blamedaveLEEDS

    The point is that they don't know what the other person is selecting! Since the two suspects are NOT communicating (and are in separate rooms) one's choice cannot influence the other's choice. Regardless of what the other person does, you are at an advantage if you rat out... And this is how you can make your suspects give away eachother.

  • @GiantNeuron this situation presumes we are not dealing with experienced criminals. firstly, experienced criminals know only to commit crimes with people they know won't talk. second an experienced criminal knows "the code": you stick to your story, you NEVER confess, and you never turn in a friend. more then likely, if two people did something that is punishable, they've co-operated b4 the investigation.

  • @GiantNeuron even when the cops come to you and say your friend confessed, you don't buy it. that is the oldest trick in the book. sorry, I'm not talking. i find out they snitched, well, they're going to fall too, and I will do my best to get to them. I will make sure people I know in other prisons know he's a rat. (this is assuming I'm a criminal who has likely done time before) if you don't confess you get 2 years? no problem, I'll see y'all in a bit over a year then (w/ good time) peace!

  • Great Job..Very Helpful

    Thanx a Lot..

  • You are amazing! I was laughing in the first 30 seconds, and I will never forget this now! Lovely smile too :)

  • i dont think prisoners would think about it that much really like weighing in how the others decision effects them but at the end you make it come together ratting out apears to be best choice

  • this is actually really interesting. You should put up another one. :)

  • Thanks alot

    Have gat exam on game theory comming up soon

  • That was great. Really well explained. For anyone who is interested I would recommend part one the documentary The Trap by Adam Curtis. It touches upon how game theory is used between states/governments and has some interviews with the great John Nash. I believe it has been uploaded to youtube.

  • Brill

  • Thanks.

  • You got the point

  • thanks, u r such a cutie

  • AWESOME

  • good shit

  • thank you so much

  • Thanks! you made this so much easier to explain!

  • It all sounds sort of interesting -- as a theory in which rational beings make decisions based on optimal outcomes -- but what does it actually describe? Has anyone actually bothered to check to see whether this theory really describes the way in which real people behave in real situations, where things like shame and group loyalty and many things beyond optimizing potential risk and loss actually play into our decision-making?

  • In Economics (although it's generally a social science, it involves economics also), as long as we can derive falsifiable predictions on the theory based on some assumptions/assertions we make, then the theory is a good one.

    So in this case, we should have assumed that other things being constant, including you have stated here, group loyalty, shame, etc. to ensure that they don't affect the predictive outcome of our application of the theory.

  • @prodprod IDK. the way I look at it as a former criminal is like this: I can stay quiet, and get A)2 years or B)8 years. or I can snitch and get C)1 year or D)5 years. C & D are not options. you don't rat, period. C & D mean U go to prison with a possible label of RAT. there are people inside you kill rats, and at the least, life will REALLY suck if they don't. this is why you only commit crimes w/ trusted people u know won't rat. u stick to ur story, never confess and never turn in a friend

  • Comment removed

  • Awesome video! Thanks, man.

  • thanks mike for the great explanation...! hope you washed ur face before you left the house that day lol

  • fucking classic- one of my favs

    great video

  • And if they're both good friends the square would look like this to them:

    10, 9

    9 , 4

  • i like this! very interesting, lets see more on game theory!

  • Wow. Look who would get 8 years! lol. Religion is a failed social science.

  • You explained this better than my lecturer! Thank you, I now understand. :-)

  • Nice video man. thanks. and yes you look like Mclovin hahaha!!!!

  • I like that !!!

  • you look so fuckin stoned out of your mind lol

  • I had thought the Prisoner's Dilemma was supposed to be thought of from the perspective of the prisoner, and that it was a crime neither of them committed.

  • Nice work, Dude. Now go and come your head and brush your teeth, LOL.

  • hmmmmmmmmmm??????????

  • gg man gg

  • He's McLovin!!

  • lmao

  • and this guy is so nice to look at.. smiling all the time.. cute and very posiive :)

  • I want to rate you 5, but currently you have 2**7 ratings and that would throw it off the exponent. I'll come back and rate it once someone breaks that beautiful number.

  • WTF

  • excellent video! getting my degree via youtube!

  • I think you should become a prof. ...you are naturally good at explaining.. seriously!

  • its easy to explain when you're own your own tho.

  • i thought going in this video would suck...however you did a fine just of explaining the prisoners dilemma...great job

  • awesome video dude, this will help me at my school work, thank you very much

  • great video man.. reminds me of a show called golden balls they have in the uk... where you can choose to split the winnings or steal.. where if they both split they get half each.... but if one chooses steal and the other chooses split the stealer gets all the cash... so the dominant strategy is always to steal... pretty cut-throat

  • Hi Rowena, This is the Video I was talking about. Watch out for the "finger thing", you'll be fine tomorrow!!

  • Good luck, Rowena!

  • Comment removed

  • great video

  • haha i think i just fell in love!!

  • So wouldn't the dominant strategy be to keep quiet because they would stay a less time in jail?

    also, great vid, really helped me with my assignment ^_^

  • It isn't dominant because.. well, if it was 2/2, 0/2.5, or 2.25/2.25, you wouldn't have a problem because you view you being better off with very little consequences to you.

    It's kinda capitalist, you try to horde the good for yourself. I'd maintain the example was prison rather than companies because you have to be a deuce, and it's easier to call prisoners deuces.

  • Wonder if the two would make up in prison after both showing as rats.

  • Unlikely they would be in the same prison since the names succest different genders. :)

  • How can this be a valid application the number of years (sentence) seems to arbitrary, I have seen this problem before but try the substituting one for zero, because as forementioned the cops do not have a case without either self incrimination(which neither would do) or collaboration on part of one of the suspects. Why would two innocent ment get one year in prison since no evidence is presented?

  • cops are very vulnerable to these strategies because they are already under control.

  • it also assumes that my goal is freedom. maybe my goal is somthing else that you dont know about...

  • the theory implies that I expect you the cop to serve yourself and betray me so....

  • brilliant assuming your prisoner is not a game theorist himself...

  • That is brilliant mate, the whole production,subject matter et al. Do you think the theory holds water? You were very convincing, but I aint sure?

  • Game theory is awesome when applied to economics.

    Ever tried auctioning a one dollar bill?

    I actually sold a one dollar bill for a $1.50

  • Look on ebay. People are selling Washington 50 state quarters for $1.50 each and they are just straight from the bank . People collect the various states to complete their collections, so they are willng to pay a premium for the convenience of not having to search for them in the change.

  • lol abt the wife..

  • Actually this is a branch of game theory which studies Non-Cooperative games, not just Game Theory, as is said in the explanation. The key feature of the Prisioner Dilemma and non cooperative games in general is that there can be cooperation but this must be self-enforcing (no contracts).

    John Nash didnt invented Game Theory; the seminal work of Von Neumann and Morgenstern is said to be the begining of Game theory.

  • Michael,

    I like the video explanation, but I want to let you know that referring to John Nash as the founder of game theory is, for the most part, incorrect. It was John von Neumann and Oskar Morgenstern with their book Theory of Games and Economic Behavior. Nash's contribution to game theory involves his study of "noncooperative" games (which led him to discover the equalibrium point which carries his name).

  • Thanks for the feedback. A little digging confirmed you're correct. As long as a theory is useful I generally couldn't care less who 'founded' it, but I appreciate the correction for those who may be concerned.

  • The day after tomorrow I've got final exam in it and I liked this video very much! Thanks a lot! you are great teacher! :) Good Luck!

    Annie

  • i have passed my exam on this topic thanks to you!!! THANKS a lot! plz do more such videos!!!

  • awesome! and you're really hot!

  • excellent job. thanks a lot

  • Nice job...exactly what I have been looking for and the explanation I needed!

  • hey man. thanks for this.

    My teacher is 65 and he did a pathetic job at explaining this. So i came to youtube and found your explanation. My teacher makes $80,000 teaching this. I think you should take his place. you'd crush him.

  • Awesome explination. So while them both saying nothing would result in the lowest sentences, to ensure the lowest sentence regardless of what the other prisoner does, they have to rat out. Thank you for explaining that. This stuff has fascinated me and has done so since the scene in "A Beautiful Mind".

  • I studied this in one of my criminal justice classes. One critique that I have for you is that I believe there is a third variable, and that would be instead of rat out, stay quiet, there is also confess. How would this play into game theory?

  • Confessing is considered the same as ratting out. Basically, coming forward and admitting that both of you committed the crime. You still get punished, but you're 'rewarded' with a lower time if you admit it.

  • No, its totally different. Confessing in not considered ratting out. Anuzis, you assume that both parties are guilty and this isn't realistically plausable. I would argue it is the norm that there is a clear line of who is innocent and who is guilty. I could fashion an argument on the basis of symbolic assailant. In short confessing and ratting out are not the same thing, could be, but not always

  • Good point. The prisoner's dilemma is only intended to be used when both parties are guilty, and when a lack of evidence makes it difficult to convict. In cases where you don't already know that both parties are guilty it's better not to use the prisoner's dilemma.

    If one party is guilty and the other innocent, wouldn't you expect both people to rat out each other naturally? The dynamics are pretty different there.

  • Sadly Nash was a paranoid schizophrenic, and his theory doesn't really reflect how people behave; it is too simplistic a model.

    One more factor which should be added to any argument, is that it is sometimes a lot more difficult to spend five years in the hole as a rat, than eight years as what they consider a good guy.

  • I agree with you. At least for me, I would rather take the chance that my partner in crime would nor rat me out and we both get 2 years, rather than figuring that he would rat and set us both up for 5 years which is way worse than 2 years. Another way to look at it is that 2 years would not be much of a problem but either 5 or 8 years are both somewhat equivalent to me as being way too much. You have to also look at what sweet revenge someone will probably give their partner if they rat - karma

  • thanks for this explanation

  • thanks man

  • You are way too cute.

  • good post . thanks!

  • You explained it better than a professor that I've found here

  • thankyou so much i needed this !

  • im really interested in game theory. it would be nice to see more vids from you

    for example questions like: PBE's, dynamic and sequential games. it would be also nice for the beginners if you show them the extensive form. and what about mother nature ^^ (strong vs. weak)

    but really nice vid. (favorited) =)

    greets

    ps: sry for my bad english...im from germany

  • Michael, what is the difference between the nash equilibrium and the term "saddle point"?

  • A saddle point is a semi-stable point. Imagine a ball sitting at the top of a hill. It is unstable, because the slightest nudge in one direction will send it careening down the hill. The opposite is true for a ball in a valley. If nudged, it will fall back to the center and stay there. A saddle is stable in on direction (front-back on an actual saddle) and unstable in another (side-side).

  • another addition ... smith said that if each individual strives for the best possible outcome the whole community benefits most. In this case each prisoner has three different possibilities concerning the stay in prison: 8, 5 and 1 yrs. So if you ignore the risks involved with going for the best INDIVUAL choice (namely staying in prison for 8 yrs compared to 1) both prisoners as a GROUP benefit most from chosing the option that possibly brings the best personal outcome - no cooperation needed

  • wonderful and interesting theory, but i mean if ou look at it practically its build on a wonky basement. in reality ratting each other out would make the investigator face the same outcome as if the both would have kept silent - there is no evidence from the interviews who really comitted the murder and therefore both should get the same punishment in both cases and NOT 5 years in one scenario and 2 yrs in the other...

    However, i know it's only a theory...

  • thanks so much !

  • too good....!!!!

  • there is a similar one , about a diamond theif and a gang land boss , too much to go into here , but these "games" only work if one party does the "dirty" on the other , the thing is people aernt generally inclined to . also one of the strongest inclinations in a human being is vengance - and we all know that!

  • i love your stuff. can you post more if you can!

  • richard dawkins showed that actually cooperating is the best stratgy and that this caused the evolution of morality in humans

    Richar dawkins documentary "nice guys finish first"

    watch?v=ZS9bcGEnN90

  • awesome!!!!!!!!!!!!!!!!!!!!!!!­!!!

  • THANK YOU!! you explained it awesome and you helped me out so much haha thanks bro!!

  • Thank you for taking the time to explain this! My professor tried to teach it in class a few weeks ago, but he didn't explain it too well and was a bit confusing. This cleared things up! ;)

  • Great!

    Is this how someone came up with the win/win, win/lose, lose/lose, lose/win theory in psychology??

  • C - explain the only rational outcome to the dilemma is both jump in the shower at the same time and to save the water 50% water wash each other - leaving 4 mins to just make sure your both very very clean.. if you get my meaning...

    not a nash solution - but a great repeated game.. just remember to always use up all but 9 mins of water!!!

    well done on the lesson.. for someone who's been partying all night by the look of it..

  • glencv21 - haven't heard of that game before. nice analogy.

  • cheers mate.. just thought it would give you a smile.. i take it your MIT or something.. watched your vid on pay rise aswel.. well explained.. but it will only work if your not expendable ofcourse.. i work in music and advertising so have to mix game theory and pyc with work and clients all the time.. great fun.. i tried your blog but it didnt seem to work.. im currently on bargaining and game theory.. just a hobby but gets quite interesting.. and people still think nash was mad ehh mate!!!

  • A - be a gent and let her use the shower leaving you only 4 mins and still 20% smelly.. but then she wont come near you as you still smell a bit...

    B - use game theory and tell her she still smells great.. hence you get the shower leaving her 20% smelly.. but you dont mind too much..

    or

  • cool lesson pal

    now do you know lesson 3 - the lovers shower dilemma -

    synario: just got back from a club in berkley say... both hot and smelly and need a shower.. you both need 5 mins in shower (yes i know women have to do all the hair shite etc.. its imaginary).. but only have 9 mins of warm (50% water is wasted per shower A 5,4 outcome.. for both lovers so only one can wash fully...ahh

    do you -

  • You can avoid the 'women needing more time to shower' -scenario by putting 2 guys in the shower - a gay version. Could be possible in San Fransisco! (without them doing any funny business while showering). But a good lesson, easily understandable! Keep up the good work!

  • Seriously great teaching man

  • Thank you for making me understand this. being in class for bout a month now and havent learned anything and to say i paid so much money when i could learn it for free on youtube.

  • You're welcome, mate. I'm working on a much better series where I'm not half-asleep while teaching. Keep an eye out :)

  • we (around 300 students) are just NOW watching this video on the beamer in a huge lecture hall. people think u look fucked up (ok u just woke up). our prof loves youtube... thats why we are watching this right now in the lecture hall.

  • oh come on. Our lecture hall isn't THAT huge.

  • About time I made it on the big screen.

  • That's cool man !! Kept Up !!

  • i'm amazed. great demonstration. congratulations.

  • BTW, can't help but wonder at how belief in G-d almighty and fear of punishment in the afterlife (worst possible payoff EVER) will lead to peace on Earth and messianic redemption (2/2 outcome)

  • That end part really put the finishing touches on to it. Very cool. 5 stars.

  • When Bob gets out of the slammer he's gonna fuck Jane up for ratting. I would say that makes 5 years the right option.

  • i learnd this in college and pay $600.

  • very interesting! look forward to the next lesson!

  • I wish I could rip this video and keep one copy for myself!

  • good stuff. can't wait for lesson 3

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