Don't move until you see it

Featured is a retrograde analysis problem I composed with the name "Quads". During the game, black captured white's rook on a dark square; who exactly captured it, and on what dark square was it captured? To quote Ben Kingsley in the movie "Searching for Bobby Fischer", "Don't move until you see it." Fans of both chess and math will likely enjoy retrograde analysis problems; put on your logical reasoning caps!

The King’s Capture:
Who Killed the Queen?:

I'm a self-taught National Master in chess out of Pennsylvania, USA who was introduced to the game by my father in 1988 at the age of 8. The purpose of this channel is to share my knowledge of chess to help others improve their game. I enjoy continuing to improve my understanding of this great game, albeit slowly. Consider subscribing here on YouTube for frequent content, and/or connecting via any or all of the below social medias. Your support is greatly appreciated. Take care, bye. :)

[ChessNetwork]

The King’s Capture:
Who Killed the Queen?:

[bobpillow]

The murderer had been very cunning and this case was driving me crazy. The black bishop looked suspicious from the very first moment, but he couldnt have done it... The biopsy on one of the victims clearly showed that the white rook died on a dark square. And a lightsquare bishop like him couldn have been the killer. His alibi was airtight, but working as a detectice for 20 years taught me to trust my hunch. After interrogating a few witnesses, I realized that a black pawn was missing. Maybe another victim? I had to go deeper. Soon I found a trail and then I realized how it all went. I had been so blind. The so-called lightsquare bishop wasnt a real bishop! The missing pawn was the murderer, who then disguised himself as the bishop! I felt a sense of relief after solving this case. I dont do it only for the money. Its unsettling to know what some pieces are capable of doing and it's my duty to make sure they pay for their actions.

[PaulFurber]

OK, it's been ten minutes and I can't even figure out how on earth Black's light squared bishop could have possibly moved from its starting position.

[wzdew]

I spent about 30 minutes on it. I picked up on the details about pawn promotion and such, but was unable to figure out the main sequence of moves. I missed the possibility of white's promotion to a rook until slightly after unpausing the video, but was too tired to continue further. Great puzzle; I enjoyed trying to figure it out. Ty. :)

[MichaelSt]

Spent a few minutes, realized black promoted to bishop, realized white pawn promote, didn’t figure out white promoted to rook, cool puzzle.

[quazzydiscman]

I was completely unfamiliar with this type of puzzle. I didn't even try it because I thought White's light square bishop was on an impossible square. After finding a few other retrograde analysis puzzles and coming back to this, I find it extremely interesting and fun! Definitely post more of these!!!

[dwebb]

i did not solve this one, and i'm a bit upset at myself for getting so hung up on "white's rook" making me fixate on only the starting queen rook and not considering a promoted rook, despite knowing after little time that black's g6 bishop had to be a promoted pawn. this was quite the clever setup and i'm beginning to suspect you may have found a new calling in this form of retrograde analysis creation. thanks for the video jerry!

[Twnkiez]

Spent about 25 minutes and got to the 6:45 mark before losing the thread. It didn't occur to me that the rook on originally on a1 MUST have been captured on a light square for this to work. I tried under promoting white's f-pawn to every other piece aside from the rook.
At one point, I had three knights for white (b3, a2, b1) to work out the underpromotion for black, but I forgot that white still had to have a knight in the end.
This was truly a devious and brilliantly crafted puzzle. Well done, Jerry!

[roykazz]

Did not manage to solve the puzzle, but the solution made me smile wider and wider as you unfolded it. Many thanks for this and the rest of your great material!!

[tobiaskristiansen]

I spend a few minutes and completely missed it! Brilliant stuff, “White’s rook” threw me off because I was thinking about one of White’s “original” rooks.

[elfakyn]

I managed to get this done! Took me about 20 minutes and it was really fun -- my thought process went more or less the same as the intended solve path. Thanks for introducing me to this type of puzzle.

that's excellent jerry, i wish i spent a day figuring it out

[MrOttopants]

I always set up the board and then knock the pieces all over the place for dramatic effect before I solve a puzzle.

[Hypervalence]

Came here after seeing the position on Twitter. I haven't watched the video yet, I promise. I genuinely gave this an effort and it took me probably an hour between solving the puzzle and typing this up, but I found and confirmed a solution. I believe white's Rook (one of three in the game), is captured by black's A-pawn on b4. This allows for black's A-pawn to make 3 captures in the game to eventually promote on b1 to turn into black's light square Bishop that is outside the pawn chain.

The game starts with two Knights, one from either side, capturing the Bishops on c1 and c8. Then one of white's Knights will eventually make a capture on black's F-pawn to clear the way for white's F-pawn to make it to f7. In the meantime, black's King is moved out of the way for white to eventually promote the F-pawn into a Rook on e8 by capturing one of black's Knights (preferably the Knight on g8). This promoted Rook must then make its way to b4. First, black moves the F-pawn on a7 to a5, but no further. Black then moves the Rook on a8 and the Queen outside, allowing the promoted Rook to get to b4 via a8, a6, b6, b4. Now that the promoted rook is on b4, black can capture it with the F-pawn on a5. At this point, black's F-pawn (now on b4) must make two more captures, one on a2 and one on b1. It will capture the Queen-side Rook and one of white's Knights, with the pawn promoting on b1 into a Bishop (which piece it captures on either square doesn't matter). Afterward, black must move the Queen-side Rook, Queen, and King back to their starting squares, move the h7 pawn to h6, and move the promoted light square Bishop to g6. At this point, if the two remaining Knights haven't already made there way to c3 and c6, they would do so. And there you have it! Wherever I didn't clarify a move was just either side making dummy moves.

This was a really awesome puzzle to work through. At first it looked simple, but the biggest challenge is black's light square Bishop and how they managed to get one outside the pawn chain, along with how black's F-pawn makes 3 captures, with one being on a dark square. Both parts were very tricky, both utilized pawn promotions, and both were tied together in the solution. Love it!

[nickcopperbottom]

You should be very happy with your self Jerry. That was great

[darrenwebb]

I got it wrong. I realised the a-pawn became a bishop on b1. I thought the a-pawn captured on b3, a2, b1 with the knight capturing Bc1 and Ra1/Rc1.
My mistake of course was what three pieces could the pawn capture, only two were available. I should have realised that meant either/or.

[flobenzo]

I noticed the light square bishop was “illegal” because the pawns hadn’t moved, and stopped assuming it was a legal board state. I should’ve looked deeper, but didnt realize it was a legal board state

[stoutlager]

I gave it five minutes. Concluded nah. Watched the solution. Yep I wasn't going to get that.

[danieljones]

Sensational composition, really enjoyed working on it

[TurtonatorGuy]

I love these videos!
I was no where near solving this one. I need more of these!