6. Search: Games, Minimax, and Alpha-Beta

Рет қаралды 449,605

10 жыл бұрын

MIT 6.034 Artificial Intelligence, Fall 2010
View the complete course: ocw.mit.edu/6-034F10
Instructor: Patrick Winston
In this lecture, we consider strategies for adversarial games such as chess. We discuss the minimax algorithm, and how alpha-beta pruning improves its efficiency. We then examine progressive deepening, which ensures that some answer is always available.
License: Creative Commons BY-NC-SA
More information at ocw.mit.edu/terms
More courses at ocw.mit.edu

Пікірлер: 263

@66javi66 5 жыл бұрын

Patrick Winston, the professor of this lecture, pass away this July... Thank you Patrick.

@joefagan9335 3 жыл бұрын

Oh sorry to hear that. RIP

@ThePaypay88 3 жыл бұрын

is it because of Corona?

@dipmodi844 3 жыл бұрын

So sad hearing that, true jem of a teacher. RIP

@BabbyCat3008 3 жыл бұрын

@@ThePaypay88 His McDonald's belly

@piyushsingh6462 2 жыл бұрын

,,🙏🏻🙏🏻🙏🏻 respect from India Rest in peace 🕊️🕊️🕊️ A great professor....

@yassinehani 5 жыл бұрын

Minimax : 16:17 alpha beta simple example : 21:51 alpha beta big example : 24:54

@ahmedmamdouhkhaled8750 11 ай бұрын

thx

@yassinehani 11 ай бұрын

@@ahmedmamdouhkhaled8750 welcome, good luck ^^

@kardsh 7 жыл бұрын

didn't pay attention in my classes, now here i am at 4 am watching a lecture from 7 years ago......

@kardsh 7 жыл бұрын

thank you for saving my ass. also, Christopher impressed me at the end lol

@darkweiss1234 7 жыл бұрын

same boat here mate

@JNSStudios 7 жыл бұрын

This was 3 year ago... this isn't 2021!

@kardsh 7 жыл бұрын

Viral Villager I came from the future

@JNSStudios 7 жыл бұрын

Nafolchan O.o

@BrunoAlmeidaSilveira 8 жыл бұрын

One of the best lectures in the series, fantastic professor and amazing didactic. Many thanks to MIT for this contribution.

@Atknss 6 жыл бұрын

Are u serious? The class and professor disappointed me. The small dwarf guy explains very well. But this professor...Not even close.

@MrEvilFreakout 5 жыл бұрын

@@Atknss can you tell me where i can find this mestirious dwarf that can help me understand AI, would be much appreciated, thank you in advance :)

@nesco3836 3 жыл бұрын

I dont know where u study or what u study but this is an amazing lecture abt AI. If u cant follow thats allows seriously conclusions about you tho

@MichielvanderBlonk 2 жыл бұрын

@@MrEvilFreakout I think he plays in Game of Thrones. Ask George R.R. Martin. LOL no seriously I would like to know too. Although I think this lecture was pretty good.

@RyanCarmellini 8 жыл бұрын

Great lecture. Very clearly explained alpha beta pruning. I liked the greater than and less than comparisons on each level. This was much clearer then just defining alpha and beta at each level.

@codykala7014 6 жыл бұрын

This was an excellent lecture. The explanation of alpha-beta pruning was so clear and easy to follow, and Prof. Winston is excellent at presenting the material in an engaging fashion. And I loved how Prof. Winston goes the extra mile to tie in these concepts to real life situations such as Deep Blue. Thank you so much!

@moosesnWoop 4 жыл бұрын

Love these lectures - think about them throughout my day. Well seasoned Lecture. Sad to hear about his passing.

@adityavardhanjain Жыл бұрын

This lecture is so good. It clears the concept on a theoretical and practical aspects both.

@DusanResin 5 жыл бұрын

Great explanation! It's basically everything you need to build any game with AI opponent in one lecture. And you can easily determinate the level of difficulty by limiting the depth level of calculating.

@avinkon 6 ай бұрын

Patrick Winston has a great teaching style with a subtle humor , childlike playfulness, enthusiasm , energetic and engaging lecture, enjoyed thoroughly :)

@johnnybegood8669 4 жыл бұрын

R.I.P. Patrick Winston, your work will last forever

@yyk900820 7 жыл бұрын

Love this professor. Calm clear explanation. Smooth voice. And humour.

@sixpooltube 6 жыл бұрын

This is the Breaking Bad of AI lectures. Epic beyond comparison. I've watched it more than once and I've learned something new every time.

@narobot 7 жыл бұрын

This is such a great video, I am pretty amazed at how anyone could have came up with this. Great lecture.

@cameronmoore7675 6 жыл бұрын

Came here for a good explanation of alpha-beta pruning, and got what I came for. Fantastic lecture! ...but what really blew me away was how *absurdly clean* that blackboard is. Just look at it!

@insidioso4304 7 жыл бұрын

Greetings from the Politecnico di Milano; thank you for these beautiful lectures!

@JenniferLaura92 9 жыл бұрын

what a great explanation. Elaborated very well! thank you

@ishratrhidita9393 6 жыл бұрын

He is an amazing professor. I would have considered myself lucky to be in his class.

@mass13982 8 жыл бұрын

Amazing professor. My hat off to you sir

@bhargavaramudu3242 4 жыл бұрын

This lecture is awesome...such a great professor he is...I absolutely love him

@EliusMaximus 3 жыл бұрын

Amazing lecture, I am very grateful that this has been recorded, thank you for spreading knowledge for free

@alakamyok1261 4 жыл бұрын

Amazing teacher, thanks to engineers of yesterday, and MIT, we have access to these gems.

@Apollys 7 жыл бұрын

Wowwww I've never seen anyone evaluate the time cost of brute forcing chess the way he did! Amazing! This guy is just amazing.

@tcveatch 7 ай бұрын

He’s only off by 10^10. While still being right. See my other comment.

@-_Nuke_- 8 ай бұрын

I wanted to say a huge thank you, this was an amazing lecture! I can only imagine the elegance of modern chess engines like StockFish and LC0... StockFish being a brute force and neural network hybrid and LC0 being a pure neural netword powerhouse... The amount of knowledge someone could get from studying them would be extraordinary! If only I could had the pleasure...

@HanhTangE 5 жыл бұрын

Seems like a really nice professor. My AI professor also nice and good teacher but leaves out some details which I learn it from here. Thanks for great courses!

@GoogleUser-ee8ro 5 жыл бұрын

Prof Winston is quite a genius in giving funny Memorable names for algorithms - British Museum, dead horse, Marshall Art etc. Also the way he explained how Deep Blue applied minimax + alphabet prune + Progressive Deepening etc immediate relate the material to real-life applications. Good Job! But I hope he could explain more on how paralleled computing helped alpha beta punning in DB.

@MichielvanderBlonk 2 жыл бұрын

Perhaps it can be organized by branch: one process takes a branch, then when it splits it also splits the process in two. Of course when b=15 that can become cumbersome I guess.

@OlivierNayraguet 4 жыл бұрын

I am into AI and Game Theory now with Columbia Engineering, I really enjoyed this presentation. So long professor.

@ohserra 10 жыл бұрын

Thank you Professor Patrick! I wish I have had some professors like you!

@jaceks6338 6 жыл бұрын

This prof explains stuff so well. Respect.

@AlexandrSudakov 2 жыл бұрын

I wish I had such a lecturer in my university :) Especially I liked the moment about cloud computing at 11:07

@stevenstefano8778 4 жыл бұрын

Great video and lecture! Required viewing from my AI professor at Pace University. Worth every second!

@shiningyrlife 10 жыл бұрын

best minimax and alpha beta pruning explanation i ever see!

@hslyu 2 жыл бұрын

You gave me a great inspiration. Rest in peace my teacher.

@maresfillies6041 9 жыл бұрын

For those who want to know where he talks about Min Max go to 25:00. It saved my ass.

@KulbhushanChand 8 жыл бұрын

+Mares Fillies Thanks , World needs more people like you.

@mekaseymour1784 7 жыл бұрын

bless you

@chg_m 6 жыл бұрын

fuck you. it starts around min 16.

@flavillus 6 жыл бұрын

thats alpha-beta part, not the original min-max.

@zes7215 5 жыл бұрын

no such thing as savex about it, doesnt matter, schoolx, scox, these gamex etc. meaningless, cepit, do, be can do,be any nmw and any be perfx. also buyer not seller, always test profx not for test

@dagual4473 8 жыл бұрын

Thanks to the guy who wrote the subtitles. It clearly made me understand beter.

@GustavoFreitas-fe4rq 28 күн бұрын

Amazing lecture!!! I'm so glad to have been recomended this.

@FreshEkie 7 жыл бұрын

Excellent, very helpful for my Artificial Intelligence exam. Greetings from Germany.

@themathaces8370 3 жыл бұрын

Beautiful lecture. Thanks very much.

@keyboard_toucher Жыл бұрын

Human chess players do use the alpha-beta approach (even if we don't recognize it by name), we just have a lot of additional tricks like heuristics about which moves to explore and the order in which to do so.

@ahgiynq 4 жыл бұрын

Thank you for these great lectures

@zfranklyn 6 жыл бұрын

Such a great, clear lecturer!

@sagarpanwar2724 4 жыл бұрын

The most clear explanation of Alpha Beta Pruning and Minimax

@richardwalker3760 10 жыл бұрын

Phenomenal lecture. Thank you.

@celialiang1485 3 жыл бұрын

Thank you for this great speech. RIP professor.

@IsaacBhasme 10 жыл бұрын

Good lecture. Elaborated very well.

@garimamandal98 2 жыл бұрын

Very well explained. All my doubts got cleared

@shubhamsawant5609 2 жыл бұрын

Cleared the outlook for Games search

@AChannelFrom2006 8 жыл бұрын

Thank you very much for these.

@junweima 6 жыл бұрын

I pray every day for more lectures

@__-to3hq 5 жыл бұрын

I'm glad I never went to a university, someone like me needs to hear or see something done a few times, this is better for me video lectures from MIT xD

@QueenGraceFace 10 жыл бұрын

This is really helpful! Great lecture :)

@berke-ozgen 2 жыл бұрын

Great and impressive lecture.

@mofakah5906 4 жыл бұрын

Came for just the minimax but I stayed for the whole lecture. Thanks MIT

@behind-the-scenes420 Жыл бұрын

Excellent instructor ever. Love from Comsats Islamabad

@maliknaveedphotography 7 жыл бұрын

Sir u R Great ! Really This is Excellent Lecture :) Thanks

@sondredyvik5815 9 жыл бұрын

Great lecture!

@amrmoneer5881 4 жыл бұрын

This is beautiful. he explained it in simple terms very vell

@dalest.hillaire5542 6 жыл бұрын

Very clear and concise.

@charlesrodriguez6276 3 жыл бұрын

Since school is online anyways and the whole course is project-based for me. I'm going to MIT online for my Fall semester.

@EngenhariadeSoftwareLuciana 8 жыл бұрын

perfect lecture!

@nXqd 9 жыл бұрын

thanks mr winston. This is so good :)

@rohitdas475 2 жыл бұрын

Pruning explained in the perfect way !!

@davidiswhat 5 жыл бұрын

Damn, this was good. I ended up skipping the proof like stuff and could only really understood the actual algorithm. Might watch more of these.

@chemicalfiend101 5 жыл бұрын

I didn't think anyone would call a bulldozer sophisticated, but they are! This course is quite eye-opening.

@nadianyc9262 5 жыл бұрын

you saved my life , thank youu

@perseusgeorgiadis7821 Жыл бұрын

Finally. Someone explained this stuff in a way I could understand

@brianbaker1124 6 жыл бұрын

wonderful lecture

@HenriqueLuisSchmidt 9 жыл бұрын

great lecture!

@robertjurjevic6580 8 жыл бұрын

thanks for this lecture :)

@maresfillies6041 9 жыл бұрын

Awesome lecture, I have a test on these topics today. :D

@larry_the 2 жыл бұрын

How'd you do on it?

@35sherminator 8 жыл бұрын

Great lecture

@ShivangiSingh-wc3gk 6 жыл бұрын

I got thrown off a little on the alpha beta part. So at each level we when we make comparisons do we look at the values from both the min and max perspective?

@shawntsai3277 7 жыл бұрын

This professor is perfect. It is waste of time to attend the same classes in other school.

@Conor.Mcnuggets 7 жыл бұрын

@ 29:34, for the deep cut, did he compare two Max nodes? or compared the bottom Min node with the root Max node?

@majusumanto9016 5 жыл бұрын

I find something here about alpha & betha, what if we're changing the position between 3 and 9 on the left tree...then the first cut off wouldn't happen... so the interesting thing is the alpha betha depended on the evaluation method... For example if you're doing evaluation from the right position so the cut-off will be different :D ... anyway thank you for the explanation... it's really clear

@debangan 3 жыл бұрын

The dude with leg up just reinvented a whole damn idea in a class. No wonder he is in MIT and I am not.

@vasugupta1 6 жыл бұрын

very nicely explained the concepts my ai lecturer couldnt teach

@wolftribe66 4 жыл бұрын

24:59 man had a tree prepared like a G

@xinxingyang4477 4 жыл бұрын

A problem I can not understand about the minimax algorithm is about the other player. Do we consider the other player can make the same calculation of the tree to a similar depth? What if they can not and made some decisions to different branches... Will that be a problem? Or not a problem?

@JITCompilation 2 жыл бұрын

Lectures like this make me wish I didn't screw around so much in high school :C should've gone to MIT instead of my crappy uni

@khairolhazeeq5426 4 жыл бұрын

I have a few questions. The first one is, is Minimax considered as a state space search? If it is is there a Goal state/node?

@cagmz 7 жыл бұрын

Can anyone explain how the deep cut off works at 28:13? Is the maximizer making a comparison from the root to the minimizer value just above the leaf?

@amitrokade1140 7 жыл бұрын

Whenever u get a fixed value of a node (here 27 at the top) , you compare that fixed value to the next deepest first node(here 1) and then again the usual way of checking nodes... I was also confused for a while there..

@MrChanyw 9 жыл бұрын

Great explanation minimax saved my ass! thankssss

@EchoVids2u 5 жыл бұрын

30:29 Shouldn't the root then be = 8 ?

@XTrumpet63X 7 жыл бұрын

I feel proud that I've been watching MIT lectures enough to have gotten the "celebration of learning" reference. xD

@axelkennedal5656 5 жыл бұрын

What does it mean?

@jamesbalajan3850 4 жыл бұрын

@@axelkennedal5656 Euphemism for an exam?

@haoyangy7026 6 жыл бұрын

Jeez this prof is so cool in the way he talks about things wish I have a teacher like that so I don't have to watch this in a class with a super bad teacher lol

@nicoscarpa 5 жыл бұрын

In the alpha-beta example, the branch that doesn't actually get created is just the right-most one that leads to the terminal node (not computed, because of the "cut"). Is that right? If it's right, than the statement "it's as if that branch doesn't exist" (24:00) must be interpreted such that the algorithm will never choose the action that leads to the right-hand node (the one

@spectator5144 Жыл бұрын

yes

@RealMcDudu 8 жыл бұрын

00:30 - funny, but Dreyfus account of this all "battle against AI" thing, is that he won (check out the really cool philosophy movie "Being in the World")

@Apollys 7 жыл бұрын

"Marshall" Arts >_< I was hoping it was a pun, but it looks like it's not...

@Griff10poldi 7 жыл бұрын

Finally I understand this :O

@livb4139 Жыл бұрын

39:02 "unfortunate choice of variable names" lmfao

@myrsinivak6993 6 жыл бұрын

When exactly does A-B prune the most nodes?

@rubiskelter 8 жыл бұрын

21:36 It's not "branching down", he says "branch and bound" from previous class.

@tcveatch 7 ай бұрын

On full depth search (13:44 ish) he says 10*(80+10+9+7) = 10^106 but it’s actually 10^116. Sure his point holds but he’s just off by a factor of 10^10=10 billion.

@rj-nj3uk 5 жыл бұрын

When the intro didn't said "This content is provided under MIT open course ware...." I thought my earphone broke.

@alikirigopoulou70 3 жыл бұрын

Does anyone know what is the app that he is using to visualize the different algorithms?

@mitocw 3 жыл бұрын

He is using Java for the Demonstrations, see ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-034-artificial-intelligence-fall-2010/demonstrations/ for more info. Best wishes on your studies!

@alpotato6531 6 ай бұрын

rip. great explanations!

@GettoFeng 9 жыл бұрын

anybody got what the student said at 42:00 ?

@bangerproductions1584 9 жыл бұрын

what does he mean by martial art example? Using your opponents force against him

@MichielvanderBlonk 2 жыл бұрын

Check out how aikido and jiu jitsu work.

@BertVerhelst 9 жыл бұрын

I wonder how much you save by using the tree of the last move as a basis for the next one, since the min player can be a human, and he might not take the branch you predicted. So the alpha beta algorithm assumes the min player will always take the option that is most in the min player's own interest, which is not always the case in computationally "flawed" humans.

@richardwalker3760 9 жыл бұрын

If the computer is the superior player, then it doesn't matter when the human makes a poor move. The computer, when doing the initial search, decided that the branch in question was "too good to be true." Thus when the human makes that move, the computer can re-discover the path that was originally "too good to be true" with less effort than it took to find it the first time (because we are one level deeper in the tree). Bottom line: Computers (when properly programmed) spend the bulk of their time analyzing the game under the assumption that the opponent is just as good as the computer. Whenever the opponent makes a poor move, the computer can recognize and capitalize on that gain relatively quickly, making the time wasted earlier irrelevant.

@MichielvanderBlonk 2 жыл бұрын

@@richardwalker3760 Probably caching values or entire trees can be of value? Otherwise you are recalculating things you've seen before.