kylemeister - Thanks for that historical information. I was particularly taken with Botvinnik-Byvshev 1952 since a line described by Krishnater as "trendy and fashionable" was played more than 70 years ago by the Patriarch. Megabase has an unannotated version of this game from the 1952 Soviet Championship.  Botvinnik played for the e3-e4 advance even though he didn't use the better known Nge2 + f2-f3 + e3-e4 setup.  The resulting attack was sufficient to win an exchange, but the game ended in a draw.  A review with an engine revealed a number of errors by Botvinnik as he approached move 40, which suggested possible time trouble.

In trying to confirm this supposition, I found that the game also had considerable historical significance. It was played in the penultimate round and was part of Botvinnik's closing surge where he won five of his final six games to pull into a tie with Taimanov for first place. A look at the Moravian Chess collection of Botvinnik's complete games confirmed that the draw with Byvshev was the only time where he failed to score the full point in his final six games. I finally found some additional details in Volume III of Masterpieces and Dramas of the Soviet Championships. The book quotes Kan as saying, "In some games, Botvinnik got into time trouble, made mistakes, couldn't always convert his advantage into a win. This happened, for instance, in the games against Korchnoi and Byvshev..." Analysis in the book by D. Goldberg and D. Rovner shows that Botvinnik overlooked a simple win on move 33 and a more involved one on move 37. Finally, an oversight on move 39 left him in danger of losing, but Byvshev missed the proper continuation.

We've touched on the Black repertoire presented by Krishnater in his Chessable course several times in this thread.  Now it has now been countered by, of all people, Krishnater himself. Modern-chess.com has recently released his two-part repertoire for White in the Queen's Gambit Declined.  Most lines begin with 1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.Nc3. Here Krishnater recommends 4...Nbd7 for Black in his Chessable course. The preview of his White repertoire on the modern-chess site indicates that he proposes to answer 4...Nbd7 with 5.Qc2, which he describes as a "rare, but strong move". Unfortunately, nothing further is given except the statement that "Black should handle this position with a lot of caution". In his Chessable course, Krishnater devotes an entire chapter to 5.Qc2, giving about a dozen lines, with Black apparently doing well.  It would be interesting if someone with access to his modern-chess analysis would give us some idea of how Krishnater's White repertoire deals with his own Black lines.

Also of interest is Krishnater's suggestion for meeting the classical 4...Be7. He recommends 5.cxd5 exd5 6.Bf4, a version of the QGD Exchange Variation that is unfamiliar to me but which evidently has become fashionable. (A ChessBase search flags it as "Hot"). It was played over 90 times last year, with big names such as Carlsen, Maghsoodloo, and Gukesh (multiple times) giving it a try. Krishnater gives White's plan as e3-h3-Bd3-Ne5. He adds in the preview video that White can support the knight on e5 with Bh2 followed by f4. This plan seems a bit Londonesque to my uneducated eye, but Krishnater says that White's idea is similar to the Nimzo-Indian Rubinstein variation with Bd2 except with the advantage that the dark-square bishop is outside the pawn chain.

FreeRepublic wrote on 12/29/23 at 20:43:37:

FreeRepublic - Thanks for pointing out Lashkin's analysis. Just to be sure everyone is clear on the line we're discussing, it's 1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.Nc3 Bb4 5.cxd5 exd5 6.Bg5 Nbd7 7.e3 c5 8.Bd3 Qa5 9.Qc2 c4 10.Bf5 0-0 11.0-0 Re8, and now instead of the 12.Nd2 main line, Lashkin suggests 12.Rfb1. Krishnater covers this move in his Chessable course. In fact, he describes it as "more challenging than 12.Nd2". As you decided, Krishnater feels that Black should play 12...Bxc3, though he comments that Black doesn't have any other choice. His lines in the Chessable course continue 13.Qxc3 Qa6 14.b3!? Ne5!!, producing complications that are not unfavorable to Black. Lashkin's follows the same line up through 13...Qa6. Here he anticipates Krishnater's knight sac, noting that the undefended bishop on f5 leaves White vulnerable to tactics based on ...Ne5. Therefore, Lashkin instead suggests 14.Bc2, with his analysis continuing 14...Ne4 15.Bxe4 dxe4 16.Nd2 b5 17.a4 which he evaluates as ±, with the comment "Black's queenside is falling apart". He also covers 15...Rxe4 16.b3 with the initiative for White. Since the Chessable course only deals with 14.b3, I posted a question asking how Black should proceed after 14.Bc2. Krishnater replied the next day saying he would include an answer to 14.Bc2 in his next update to the course.

BTW - I'm glad to see that you bought the course. It offers quite a bit of material, and Krishnater seems very responsive to questions. I might go ahead and ask him about the position in Tan's line that you examined in Reply #47.

Nernstian59 wrote on 12/22/23 at 22:49:16:


I played this out, mostly SF vs. SF, sometimes with my input. SF stubbornely prefers White, then often plays to repetitions! At this point, there seems to be two ways:  18...Qa6 which soon leads to a trade of queens and 18...Bd7!?. You get what you see:  Unbalanced pawn majorities and opposite colored bishops. As Black, I would want to keep the queens on the board.

FreeRepublic wrote on 12/29/23 at 20:43:37:

Historical note: 12. Rfb1 was a "N" in the Informant about 25 years ago, played by Piket (who annotated the game) against Milov (who replied 12...g6). Later that was cited in ECO as equal (or unclear, in the case of a couple of deviations). 

(By the way, Piket was interviewed on the ChessBase India YouTube channel a few months ago. I found it a bit jarring since I still had a mental image of him from when he was about 20.)

FreeRepublic - There's coverage of the variation you discussed in Reply #30 in Chessbase's Opening Encyclopaedia. The analysis is by Lars Schandorff and was first published in ChessBase Magazine # 121. Schandorff uses a Ragozin move order (1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.Nc3 Bb4 5.cxd5 exd5 6.Bg5 Nbd7 7.e3 c5 8.Bd3 Qa5 9.Qc2 c4 10.Bf5 0-0 11.0-0 Re8 12.Nd2) to reach the diagrammed position in Reply #30. Here Schandorff only considers 12...g6, which is understandable. It's easily the most commonly played move and is, as you note, the historic main line.

Now Schandorff dismisses 13.Bxd7 saying that the move "...wins some time because Black must take back with the knight. Still, several games suggest that Black is OK.". He only considers 13.Bh3, which he describes as "The most challenging move". He agrees that now after 13...Bxc3, 14.Qxc3 is good. In fact, he says that 14.Qxc3 Qxc3 15.bxc3 reaching a slightly better ending is "surprisingly strong", although he adds that after 15...Ne4 16.Nxe4 dxe4, White must find 17.Bg4 ("Karpov's deep move"). After 17...Nb6, 18.Be2 preserves the bishop pair and allows White to maintain a long-term edge. Schandorff presents the game Karpov-Milov, Cap d'Agde-A 2002 as a demonstration of how White exploits his advantage.

Schandorff also examines 13...Bf8, protecting the kingside. He says it's a flexible idea that needs to be taken seriously, but adds that Black has wasted some time, giving White a free hand. Using illustrative games, Schandorff then shows that three continuations, 14.Rfe1, 14.Bh4, and 14.a3, all give White some initiative and good chances for an advantage.

Most of Schandorff's effort is focused on 13...Kg7, which he calls "A good waiting move". He only analyzes the reply 14.Rae1, which he shows to give good attacking chances due to an eventual central breakthrough with e3-e4. He concludes that this variation, which he calls the old main line in the Ragozin, is not quite satisfactory for Black.  The second player "has tried many moves, but theoretically White has found pleasant antidotes to them all". However, Schandorff does note that in practical play, matters are different. The positions are very complicated and difficult to play OTB. Thus, Black has his share of chances.

CBM 121 was published in late 2007, so there's been quite a few years for new Black approaches to be unearthed. The diagrammed position in Reply #30 is the starting point for a couple dozen lines in Chapter 2 of Krishnater's Chessable course.  The chapter title is "Manhattan - Big Main Line with 8.Bd3", so it's clear that the variation is theoretically important. (Note the variation is called "Manhattan" since the position of interest is reached via 3.Nf3 Nf6 4.Nc3 Nbd7 5.Bg5 Bb4 6.e3 c5 etc; i.e., a Manhattan move order). Krishnater concentrates on Schandorff's main line: 12...g6 13.Bh3 Kg7 and now in response to Schandorff's 14.Rae1 Ne4 15.Ndxe4 dxe4 16.Bf4, he gives 16...Nf6. (Schandorff considered 16...Nb6 and 16...f5, which were the only two moves to be played more than once at the time of his writing). Stockfish prefers 16...Nf6 and evaluates the resulting position as =. Krishnater analyzes several lines arising from 16...Nf6 and shows that Black doesn't enjoy straightforward equality. He often has to give up the exchange to win the c3-pawn and gain sufficient activity to maintain the balance.

Although Schandorff preferred 13.Bh3, there's some difference of opinion regarding White's best 13th move. The ChessPub Guide "QGD/26 Ragozin System", published in April 2022 seems to favor 13.Bxd7, saying "White gives up his bishop but gains time for development. This approach is more popular than the retreat 13.Bh3, which costs a tempo, and in most cases does not secure the bishop from exchange with its Black counterpart anyway." This comment apparently originates from Ruslan Scherbakov's tenure on the 1.d4 d5 2.c4 section, specifically from his notes to Arencibia-Disconzi da Silva, Buenos Aires 2005. Now, after 13...Nxd7 14.f3, the ChessPub Guide analyzes 14...Nb6, following Korotylev-Landa, RUS ChT Dagomys 2005 and concluding that White has better chances. Krishnater's suggestion is 14...Bf8 15.a3 Nb6 16.e4 Bg7 17.e5 Bf5 followed by ...Nd7 and ...f6 to eliminate White's space advantage. Stockfish evaluates the position after 17...Bf5 as =, but it also suggests that White might have a slight edge with 17.Be3 instead of 17.e5. Krishnater does cover 17.Be3 in his course giving 17...Bd7, when he says "White keeps a space advantage, but Black has a better pawn structure and the bishop pair. Comp calls it equal, but I think it's easier to play as Black." Stockfish and Dragon 3.2 both give +/= for me - could this be another case of the engines' preference for space?

In the ChessPublishing update for April 2022, Justin Tan also covers 13.Bxd7. After 13...Nxd7, he comments "in my opinion Black does not completely equalise after Kramnik’s move 14.h4". On the other hand, in his notes to J.Pinter-A.Greenfeld, Beersheva 1991, Scherbakov says of 14.h4: "Logical, but probably not the best".  He goes on to note that protecting the bishop on g5 could well be pointless since it's rather useless on this square and often moves elsewhere. In any case, Krishnater has multiple lines with 13.Bxd7 in his course, covering 14.Bh4 with 13.Bxd7 Nxd7 14.h4 f6 15.Bf4 Bxc3 16.bxc3 Nb6 17.f3 Qa4. Here he ends his line with the comment, "forcing the queen to an inferior square." Interestingly, Tan reaches the same position in his notes to Jinshi Bai-Ding Liren, Hangzhou (3.2) 2022 in his April 2022 update. He continues with 18.Qb1 and concludes that "Black still needs to work to claim full equality". In the position after 17...Qa4, Stockfish gives Tan's 17.Qb1 as its first choice, with an evaluation of +/=. In contrast, Dragon 3.2 and Lc0 both give =, so any edge seems to be quite small.

Finally, there are the newer 12th move alternatives to 12...g6. As kylemeister pointed out in Reply #31, Tan felt that the most reliable move was 12...Qa6 with the idea to follow up with ...h6, ...Qc6 and ...Nb6. Krishnater includes 12...Qa6 in his course as an alternative line, giving a handful of variations including one that has Black reorganizing his pieces in a manner similar to that described by Tan. And to answer the question in Reply #30 about 12...h6 being in Krishnater's course - the specific move is not, but ...h6 is usually played on move 13 or 14 after 12...Qa6. As noted earlier in this thread, Erigaisi has tried 12...h6 a couple times this year. In both games, he's followed up with ...Qa6-c6, so he apparently played a transposed version of Tan's plan.

Also (Manhattan Ragozin + QGD Exchange with Bb4) will be covered in the upcoming reportoire for Black with Angelika Valkova & GM Gyula Pap

Good times for the Ragozin