Wait, a one hour sequel to the video that inspired me to write my own Chess engine and eventually became my Bachelor thesis? HELL YEAH!:D

an hour long ? We are blessed, thank you Sebastian

Please don't apologize for a part 3, I'd love to see it!

18:25 An easy way to find if the bot has improved is performing a sign test. We model the number of wins for v7 as a binomial variable X~B(n,p) with number of games(n) = 1000, and hypothesise that probability of a win(p) = 0.5. If we treat every 2 draws as one loss and one win, we can find the probability of 365 + 282/2 = 506 wins. Finding the probability that X >= 506 gives us a p-value of 0.364. At a significance level of 0.05, this means we cannot conclude that the v7 bot is better than v6c and would need a larger sample of games to be sure. TLDR: we cannot say there is a significant improvement

The method to calculate the probability of one engine being better than another based on game outcomes is called the Sequential Probability Ratio Test (SPRT). The CLI-based match runners that the chess programming community use to test their engines have this capability built-in, and can automatically run a test until the probability of improvement exceeds some desired bound. The most popular one is called cutechess-cli, which works with UCI chess engines

50% of why i love watching these videos is about the code. The other half is about the fantastic story telling along the way. Incredible video editing (animating code edits, animations between code/variable changes and the actual impact of those changes in the final product, statistic tracking and animating, good pacing throughout the video, no chapter feels slow or boring). And I could keep going for a while. I’m curious what kind of tools you use to do this editing. It’s really awesome and I hope you keep making these kinds of videos for a very long time!

Ngl the fact that a chessboard is 8x8 is a happy little coincidence that makes chess programming easier since all the values fill well

This one really deserves the title "Adventure" and is exactly what you need when you can't sleep at night because you keep thinking about your terrible maths exam from 2 days ago. Thank you :D

You know today is going to be a good day if Sebastian uploads a new video 😊

This is really cool! I've been a chess nerd all my life so seeing this is like magic to me. Separately, do you have plans to continue working on your explaining computers series? And, if so I'd appreciate it if you would share with us! I really think that series is incredible. Thanks!

50:25 "So I may need to subject you all to a Chess Part 3 in the future." YES! My body is ready.

What impresses me the most is how dedicated you are to tackle new ideas and then return later to improve them. Usually when I start a personal project I put a lot of time into it and then kind of abandon it and move on to something else You are a true inspiration

Blame on you, Sebastian! I went down the rabbit hole of a chess engine from scratch of my own. I made bit boards , alphabeta search, nn evaluation, Montecarlo tree search and many other micro elements retrieved here and there as ideas. A wrote the code from zero 3 times, changing programming language as well as approaches. After two months I am dreaming of bishops moving only on diagonal bits (don’t know, in the dream a “diagonal bit” has totally sense). In fact it has been a huge journey and I am happy I had the stamina to overcome the several difficulties and the final result is definitely mediocre but totally mine and this is enough. You started the interest in the topic I had since I was a child as a personal programming challenge. Very nice job pal. Thanks a lot

At 31:58 this sounds like something that could utilize the "pdep" assembly instruction on pretty much all 64 bit processors. There's a C# binding for the command called ParallelBitDeposit. The purpose of the command is to take a 64 bit value you have, and a 64 bit mask representing the locations you want the bits from that value to be distributed over, and it deposits the bits from the value into the spots defined in the mask. Being able to do that in a single instruction sounds like it could heavily speed up that part of the application.

all this makes me realise just how terrifying stockfish is holy fook.

Always a pleasure to watch another Coding Adventure.

My English is so little and this video is so fabulous. Thank you Sebastian! This programming - chess content is really interesting

An hour long coding adventure featuring cats, that somehow makes me feel both relatively inedequate at coding but also motivates me to 'go do stuff!'... My day couldnt get any better! Honestly thank you for these videos, the animation work is so clean and you can tell how much effort goes in

I would love a part 3! Also I loved how long this one was :)

Currently writing a study about coding my own chess engine. Your video was the first and most impactful one I watched to inspire myself for my study. And now I get to have part 2?! Thank you very much Sebastian! Holy, I just finished watching the video and damn, I was hoping for copper but found a pile of gold!

18:24 You wanted to know if this is better or just random. Well, I calculated the P-value(*) using a two-tailed Binomial test(**) for every version you tested: Match | Wins-Loss | P | Better? V2b vs V1 | 409 vs 270| 1.1e-7 | YES V3 vs V2b | 399 vs 387| 69% | Random V3_64vs V2b | 386 vs 246| 2.8e-8 | YES V4 vs V3_64 | 433 vs 237| 3.3e-14 | YES V5b vs V4 | 337 vs 273| 1.0e-3 | YES V6 vs V5b | 393 vs 310| 1.0e-4 | YES V6b vs V5b | 298 vs 309| 68% | Random V6c vs V5b | 385 vs 276| 2.6e-5 | YES V7 vs V6c | 365 vs 353| 68% | Random V8 vs V7 | 415 vs 325| 1.1e-7 | YES V9 vs V8 | 347 vs 367| 48% | Random V9b vs V8 | 396 vs 341| 4.7% | Random (debatable) V10 vs V9b | 447 vs 275| 1.6e-10 | YES V11 vs V10 | 477 vs 221| 1.6e-22 | YES V12 vs V11 | 397 vs 238| 2.9e-10 | YES The notation "2.8e-8" means "2.8*10^(-8)" that is 28 in a billion odds, 1e (*)What does the P-Value mean? It is the chance we would still get this result if the players were equally good. A lower P means more likely not random (**)How do we calculate that? Using a two-tailed binomial test (If you already know how that works you can stop reading now) Our null hypothesis (which we hope to debunk) is that both players are equally likely to win. (I ignored all draws, and looked only at the games with a winner) The P-value is the likelihood that we would still get this result or something less likely if our Null hypothesis is true. So for the 365 wins and 353 losses, the P-value is the chance of getting either 365 wins and 353 losses, 365 losses and 353 wins, 367 wins and 352 losses and so on. This is a "two-tailed" binomial test, and you can look up the formula for calculating that on Wikipedia. A low P-value means that it is unlikely (But still possible) that we would get this result if the players are equal. I decided that if P

I look forward to Chess Part 3! Also, this is such a SPECTACULARLY good explanation of so many difficult concepts of chess engine design. The magic bitboards part especially. Well friggin' done!

Wow! I've rewatched the first part many times and now its finally time for the sequel. Good job, I can't wait for the next part!!

This is so so good as always, hoping you will make a part 3!

This is an awesome adventure through the associated code! I really appreciate the cleverness of the use of bitboards to represent various aspects of game state, and the various ways you show of working with them through mathematical operations that stand in for more conventional approaches such as iteration loops. One thought that crossed my mind repeatedly was taking all the metrics you employ, turning them into inputs for a neural net, and utilizing machine learning to let it experiment with various combinations of weights, to arrive at optimal values. I realize this is much, much easier said than done, since it amounts to many dozens of inputs. Anyway, great video, as always!

I’m subscribed to a few hundred different UKposts channels, some inactive and others active. Yours is the only one I have notifications set up, so I get notified when you upload a new video. I absolutely love watching your videos. They are paced and explained to perfection, and you tackle some really interesting subjects. By far my favorite UKposts channel. Thank you!

10:48 this is such a good reaction gif. ori is clearly an excellent performer. she has mastered the art of less is more

I am a computer science professor, and I teach heuristic search and Game AI each year. I am blown away by your animations and your detailed explanation of these concepts. I wish I had the time per lecture and video production skill to be able to make content like this for students. 27:51 - Sometimes adding calculations to the evaluation which theoretically improve things can cause your evaluation to be a bit slower, meaning fewer nodes / depth searched. There's not exact science to this, and this is why your evaluation is so important 28:16 - You can eliminate some of the conditionals that you have here by doing clever tricks like saying numIsolatedPawns += (1 - (friendlyPawnsBitboard & Bits.adjacentFilemask[pawnFile] > 0)). Doing the math directly on the result rather than using an if-statement helps eliminate slowdown due to branch prediction. In practice this may not actually make the program any stronger, and the compiler may be smart enough to do this for you anyway, but it's something to think about. Final comment: Did you tie-break scores with the number of moves performed? I did not see this anywhere in the video, but you definitely want to be taking 'quicker' checkmates than later ones due to the incomplete nature of the search.

i'm sure you've heard by now how amazing your work is. what i want to point out though, is how remarkable your patience is. Sticking through gigantic projects like these and keeping on through all the bugs and edge cases is an amazing feat!

18:31 Not a statistician, but I think I can calculate the P-value (the chance that the test would have given the exact same results or less evenly distributed assuming winning and losing both have a probability of 0.5) anyways. I assume the games that are drawn were never played, im pretty sure that's an assumption that you're allowed to make. Before finding the P-value, I first want to explain how you would find the chance that exactly 365 out of 718 are won. This question is the same as asking 'suppose you threw a fair coin 718 times. What are the chances that it lands heads exactly 365 times?'. If you throw a fair coin 718 times, there are 2^718 possible sequences. Out of those sequences, 718! / ( 365! * (718-365)! ) contain heads exactly 365 times. Let me explain: " suppose you have 718 tickets with each a unique value between 1-718. If you lay them down in a random order, there are 718! different possible sequences. If instead you paint over 365 tickets with yellow paint (analogous to getting heads in the coins analogy, or winning in the actual problem) before laying out the sequence, the amount of different sequences suddenly becomes 718! / 365! as for every new way of laying out a sequence, the yellow tickets would have otherwise had 365! different ways of being ordered. If you paint over the other 353 tickets with blue, the amount of different sequences becomes 718! / 365! / 353! " Thus, the chance to get heads exactly 353 times is 718! / ( 365! * (718-365)! ) / 2^718 which roughly equals 0.0269. Now, to calculate the P-value, we add up ((the chance to win 365 times out of 718) + (the chance to win 366 times out of 718) + .... + (the chance to win 718 times out of 718 times)) + ((the chance to lose 365 times out of 718) + (the chance to lose 366 times out of 718) + ... + the chance to lose 718 times out of 718 times)) = 2 * ((the chance to win 365 times out of 718) + (the chance to win 366 times out of 718) + .... + (the chance to win 718 times out of 718 times)) which roughly equals 0.68. This is not low enough to conclude that the newer version does not have a winrate of 50% at all. Let me know if anyone has any questions!

I love this some months ago, inspired by the first video, I also decided to give writing my own engine a try. you have no idea how much I needed that boost of confidence to keep going and know that I'm going in the right direction. when I have some time and a stable build I will definitely make our engines play a game and let you know the result. you are by far my favourite (coding) content creator and I hope you never stop uploading once in a while.

Half way throught but can safely say that this is another fantastic video. Pace, quality and obviously the subject is unmatched. Thank you Sebastian for this ❤

Love this video series. I did a chess game for my A level comp sci project (A level is a qualification taken at 18 in UK). Spent hours watching and rewatching your first vid as it was released right in the middle of that time. This vid was awesome too! Would love to see more in the future :)

Love these videos! It was very satisfying to watch it slowly get better and better 😄

I've watched that first video along with that tom7 video countless times, and I'm so excited to see a sequel!

Thank you Sebastian for such an interesting and informative video. You're definitely my favorite programming/development creator on UKposts! I absolutely adore how you approach your projects with such enthusiasm and care, especially when you go the extra mile to provide enlightening visualizations and demos in your videos.

OMG, Sebastian. Even your code editor color theme is aesthetically pleasing.

Yay, you're back! I really love watching your videos, it's always a surprise when a new one is released.

I love this video. The first was one of my favorites, and this is a well-made sequel with the same relaxing tone and pacing that anyone can understand. Thank you!

I really enjoy coding various things/projects and watching your videos really is enjoyable, as i can see how various things work, watch an effective planning process, and do all of this with pleasant visuals and audio. the editing and overall content of these videos is really great, and i cant wait for more videos. thank you for making such great content!

Sebastian's videos have been such an incredible inspiration for me! They sparked my passion for programming my very own chess engine. And now, seeing him in action, making it even more efficient, is truly motivating me to strive for improvement and enhance my skills. Thank you so much, Sebastian! You've made my day incredibly special. Sending lots of love and gratitude from India. ❤

best series ever, the storyline is perfect

I'm so excited to watch this! Your first chess video was what brought me to your channel, can't wait to see what you did this time :).

This is absolutely amazing! I haven't actually watched your first video (i'll make sure to do that now), but this video is so interesting as a chess player and programmer myself - I actually tried making a program similar to that recently but gave up on the idea. Perhaps I'll continue now with the new motivation I've obtained from this video and what I've learned. Thank you!

Thank you for recommending that 30 chess bots suckerpinch video! It's really great for people who enjoy similar content and one of the most under-viewed videos on youtube. These two chess bot videos of yours have been the only things to scratch that same lovely itch for me, so thank you even more for making such amazing videos like these.

Your last video was super entertaining and informative,,,, saw part 2 and I immediately clicked! Thanks for the vid :)

This was such a great sequel to my favorite video of yours! Your videos are so inspiring, keep it up :)

Someone mentioned your channel in passing and I've been having such a good time watching your videos. Seeing you tackle these problems and clearly explain each approach with the code on-screen really helps make the whole thing feel more approachable.

"makes more sense than En Passant at least" En Passant was added because moving pawns 2 squares was added to speed up the early game. Originally pawns could only move one square, so it was impossible for pawns to "jump past" each other to avoid capture. En Passant was added to allow for pawns to retain their same amount of control while keeping the speed of the early game fast.

A sequel to my favourite coding adventure video! You never disappoint

I KEPT REWATCHING THAT FIRST VIDEO CUZ I LOVED IT SO MUCH! THANK U FOR MAKING ANOTHER AND BLESSING US WITH AN HOUR OF AMAZING CONTENT ❤️❤️

This is one of my favorite things you've done on this channel, please do a part 3!

I never fought about that, but I think you're my favorite UKpostsr among the hundreds I watched. 1) Inspiration for coding 2) So much I learned 3) So eye pleasing graphics Wow! Keep up the work 👍

I have been working in a chess engine myself in Rust. I had played chess for a few years but only your last video on this series made me excited to start. Great stuff!

Exceptionally good and very interesting video Sebastian, thanks for all the hard work. I really hope you make a 3rd one to see how much you can improve it again.

I'm so happy you've come back to this project - it's amazing!

i live for your cat b roll footage

I was really hoping you'd come back to this! Your previous video inspired me to start working on my own chess engine, which after many iterations is now the project I'm most proud of!

Fantastic video as always Sebastian! I've watched Tom7's video several times so it's awesome to see it called out!

Amazing work! Love your thorough explanations on the inner workings of a chess program.

wasnt expecting a second part of this. the first chess video of you was already my favorite video and it was very detailled. i cant even imagine whats in this video :)

You've a very powerful talent Sebastian. I'm absolutely uninterested in chess or board games in general. Yet, when you make a video like this my fingers start to itch to create my own chess engine. There're very little other videos as inspiring and motivating as yours. I hope you are aware of the impact your videos have. Thanks so much for making these.

oh my god ive been waiting for a followup for so long this has made my day, you even inspired me to make my own chess engine thank you!!

We'd all love to see a third video!! And beating your version one that badly wow!!! Amazing improvements on your end

I don't often leave a comment but I just have to here. Wow. Gosh I love watching this stuff. Watching a Sebastian Lague's video is a fun activity all by itself. Thank you so much for the 1 hour long content.

I reallly like this video and as someone who also created a chess bot (much weaker) I know to appriciate how much work you putted into this video. I also want to add that the bot isn't overrated at all. I am 2600 in bullet and blitz and played some bullets against it and it outplayed me most of the time. By the way I couldn't help but notice that you are also a decent chess player by your way of thinking

I really love your videos. I discovered your channel about a year ago. So calming and interesting. I really enjoyed the flying delivery game round Earth :).

Your videos are gold, Thank you I appreciated every single seconds of this video. Your previous video about your chessbot was amazing and inspired me to make my own chessbot and this one is even more entertaining.

I love this video concept so much!! As a chess player and evolving programmer, you have officially just made my day! btw PLEASE make a third video, this is so enjoyable to watch...

You made a mistake on the passed pawn mask. The two squares immediately diagonal to the pawn should not be included. If it's your turn to move and there's a pawn that could capture you, you can simply move the pawn forward to get past the pawn. You could also potentially capture the enemy pawn to make your pawn a past pawn.

I always look forward to your videos man.. This is a treat

I've been coding for a while and worked on a few big projects, but I've never really relied on bit manipulation to keep track of and manipulate data. This video was amazing, and it greatly increased my appreciation for binary operations and bit manipulation. Even though I understood what it was before I never really liked it, but now I'm definitely going to make a point to use it in my next project. Fantastic stuff as always, can't wait for the next one.

It looks like you need to add King safety in the bitmap as well, it is not penalizing open space near king it looks like. Great video btw, never knew where the entire hour went!

Man, your vidoes are production quality, your narrations are well written and structured. No sure why this isn't on master class. Please do keep up the good work.

Awesome video! It’s cool to see you doing a lot of the things I did for my checkers engine, and some things I haven’t done yet!

It's always a good day when Sebastian posts a video. And always a terrible month afterwards, as I get inspired fo start a similar project and innevitably fail.

Another simple improvement would be to use the “allowed moves” bitboards in your evaluation. You can combine it with the square scores as well and add all of the possible moves weighted by the square score. This would solve your “rook stuck in corner behind bishop” problems! Very cool video!

the first video was absolutely incredible, and this is too, I love this content and keep it up!!! pls pt 3

Awesome video. Very entertaining and informative at the same time. I thought 20 minutes have passed and then the whole video ended. Really enjoyed the explanation on every addition. Keep it up!!

I always love your videos! So cool!

If a coding adventure comes out, you know you have to binge watch it immediately 😂

I watched what is now part one last week as it is one of my favorite UKposts videos, how great that it now has a sequel!

Would love chess engine number 3! The original video was how I found your channel (and then binged the rest of the videos) Slowly tempting me to make an engine for Gungi, even though it would be way more complicated. Lovely to watch everything you do, keep it up!

Loved this video, please more uploads just like this! :)

I would love to see you do a triangulation series, covering things like Delaunay and Constrained Delaunay Triangulation.

Amazing! What a great video. I am always so happy to see a new video of yours!

A really incredible video, thanks you for showing actual code and explaining optimisations you used. The Magic Bitboards remind me a lot of perfect hash functions.

Very cool of you to narrate these experiments your cat made!

I'm all in for a PART 3. DO IT!

I was waiting for this video!!! Thank you!!!

Yesss! Even the anticipation of this video had me excited! I'm so stoked to watch it

BMI2 would actually help with the bit manipulation a lot, it's a common x86/64 extension in most modern processors

I don't even know how to play chess but was so invested lmao

Great video, I loved the explanations and new ideas you came up with from start to finish! :)

Damn, another great video of arguably one of the best and definitely the most relaxing channels out there! Love your videos!

An interesting challenge would be to make a non-random bad bot, that feels like a human beginner.

I feel the most major improvement to make here is having CAB care a lot more about the safety of it's king, and the vulnerability of the opposing king.

This is a great video not only well made but also combines my 2 favorite things chess and coding.

Insane video as always. Please continue!

Great stuff, looks like bullet rating is stabilizing at 2700. In my (I'm 1950 rated) game I still got an early lead though of +2. I think there is the most room for improvement. Something like piece moveability could be factored in (a queen/rook/bishop is much better if it is not blocked by other pieces).