Sub-wiki re: Queen's Gambit Declined Ragozin Variation

Here's the Sub-wiki re: the Queen's Gambit Declined, Ragozin Variation (only a short paragraph is given):

https://en.wikipedia.org/wiki/Queen%...ion:_4.Nf3_Bb4

One move order the Ragozin can be reached by is 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 and then 4...Bb4 can start it, and this is the only move order the sub-wiki lists.

More interesting to many players, however, is that the Ragozin also can be used as part of a complex that includes the Nimzo-Indian Defence (besides the Catalan, as we'll see). That is, the Ragozin can be reached via 1.d4 Nf6 2.c4 e6 3.Nf3 d5 and now 4.Nc3 Bb4 can start it.

Note that versus 3.g3 Black can choose from 3...d5 (normally leading to a Catalan), 3...c5 and 3...Bb4+. Going back to 3.Nf3, Black can choose from 3...b6, 3...c5, 3...Bb4+, besides going into QGD territory with 3...d5 (possibly leading to the Ragozin). Thus it would seem White gives Black at least one more option by playing 3.Nf3 instead of 3.g3. However, aside from that, note that White can still choose to steer for a Catalan after 3.Nf3 d5, with 4.g3. Not only that but after 4.Nc3, if 4...Bb4, White does not have to stick to Ragozin paths, but can transpose to a Rubinstein Nimzo-Indian line with 5.e3 (though both sides have lost some options).

Here's a link to a thread on the Queen's Indian Defence (1.d4 Nf6 2.c4 e6 3.Nf3 b6):

https://www.chesscanada.info/forum/s...9140#post39140

Here's a link to a thread on the Bogo-Indian Defence (1.d4 Nf6 2.c4 e6 3.Nf3 Bb4+):

https://www.chesscanada.info/forum/s...Indian-Defence

[edit: below is a link to a thread on the Catalan.]

https://www.chesscanada.info/forum/s...atalan-Opening