Analysis of the QGD (Queen's Gambit Declined

I have made a lot of comments and analysis of the QGD (Queen's Gambit Declined)

I know - a lot of text!

This is the Catalan opening, not the Queen's Gambit Declined. Still, nice to raise awareness about the Catalan which is my favorite opening

It is possible to argue that the Catalan is a branch of the QGD but this is not really true in the same way as the Semi-Slav is not a variation of the Slav - the openings are just too different. Nonetheless here are some of the most interesting variations of the Catalan, including some lines with sacrifices:

The idea of 10Bd2 is to restrain c5 after 10....Nb-d7 11Ba5 Rc8, although even here white's advantage is not massive. 10....Be4 11Qc1 bb7 disrupts that plan 12Ba5 Nc6.  After something like 12Bf4 Nd5 13Nc3 NxB 14QxB Qd6 white's problems getting somewhere here make white's against the Berlin look like a picnic.

The modern mainline is to play 8.a4 which I think is more effective at the top level at the moment. However in this old mainline Marin recommends the move 12.a3 which looks interesting

8a4 was thought to be white's best try in Kotranias's "Beating the Flank Openings" from the 90's. In fact since became Karpov's main defense in late 70's, white's main line as shifted between 8a4, 8Qc2, and 8Ne5 with it being hard from white to show anything in any of them. 

12a3 after 12...Nb-d7 is either a waiting move for 13Ba5 etc or playing 13b4 to try prevent c5. Against 13b4 black can 13...Ra7 then Qa8 and a5.  After  13Ba5 Rc8 14Nd2 Nb6 white can prevent c5 definitelty with b4, but Ba5 looks weird, or allow c5 with some tricks with 15Rd1 c5 16Nc4 but black comes out ok.

This is a pretty robust line for black, and the ideas are fairly simple, neutralise Bg2 with b5 and Bb7, or Bd7-c6 in the a4 line, then arrange for c5.