fredthebear: D39 Queen's Gambit Declined, Vienna Variation has now been corrected.References:
- https://learn.chessbase.com/en/page...
- https://en.wikipedia.org/wiki/Queen...
- https://www.modern-chess.com/chess-...
- https://www.goodreads.com/book/show...
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- There are several hundred Queen's Gambit videos available on-line for free. Your favorite source of reliable chess videos likely has something on the topic. Popular streamers like GothamChess, Anna Cramling, and thechesswebsite are usually good places to start.
- Video of the game above: https://www.youtube.com/watch?v=st4...
FTB has long distrusted the CGs opening labeling system, having sent in so many endless ECO corrections that it's become pointless. I should have known that D39 is infected with errors like the rest. To be fair, it's an almost impossible task to correctly label so many games from so many sources.
As suggested, ...Bb4 signals the QGD Ragozin Defense. The continuation BxNc3 is not necessary; the bishop may capture, stay in place, or retreat and it's Ragozin waters regardless.
Retreating to ...Be7 is sometimes played, generally on the 8th-13th ply as in the game above. The readers can find contemporary Ragozin games with ...Be7 involving Ding Liren, Magnus Carlsen, Ian Nepomniachtchi, Wesley So, etc. in this database. However, ...Be7 is definitely not the main line.
Given the Opening Explorer page Queen's Gambit Declined, Ragozin, Vienna Variation (D39) labeling Ragozin all over, one certainly thinks these D39 games are all Rogozins.
The first appearance of 4...Bb4 is not until 1933. Twenty other games have already been posted?! Viacheslav Ragozin himself did not play 4...Bb4 until 1936: A Budo vs Ragozin, 1936
FWIW, sometimes 4...Bb4+ or 5...Bb4+ is played before the Nc3 has been developed and we're still in Ragozin waters IF Nc3 is played.
With that, FTB will leave it up to the readers to decide which D39 games are properly labeled Ragozin, and which are not.