jitb wrote on 06/20/09 at 15:46:45:


They're not doing it solely to get a QGD on board. Some of them simply play the Catalan as black (like myself), and don't mind the transposition.

Against 3. Nc3 some play the Nimzo-English, or go ahead with the QGD anyway as black.

You can't punish black for playing this way, even if it started out as a flank opening.

The first one TN listed is most accurate. 

I'll just add that 1. Nf3 e6 2. c4 d5 should not be met by 3. g3 as 3...dxc4 appears to equalize. More accurate would be 3. d4 allowing the possibility of a QGA, unless black plays 3...Nf6 which meets 4. g3 with a Catalan.

A lot of players will walk themselves into the Catalan without thinking after 1. Nf3, whereas when it comes up via 1. d4/1. c4 they're more wary of it.

That being said, as much as a Catalan devoted player as I am, I think white needs to be able to play 3. Nc3 just as well, and handle the QGD transpositions/Nimzo-English. You never know when the Catalan is going to go out of fashion again due to some equalizer coming up that everyone suddenly starts playing, so restricting one's repetoire is never a good idea.

I don't have time to answer your question in detail, but checking the footnotes in ECO A (where transpositions are), Emms's 'SO: King's Indian Attack' and Davies's 'Dynamic Reti' are logical places to start your research. 

A few random examples:

1.Nf3 Nf6 2.c4 e6 3.g3 d5 4.d4
1.c4 c6 2.Nf3 d5 3.b3 Nf6 4.g3 (this is a Reti rather than a Catalan but the positions would be similar with a later d4 by White)
1.c4 Nf6 2.g3 e6 3.Bg2 d5 4.Nf3 Be7 5.0-0 0-0 6.d4
1.Nf3 d5 2.c4 e6 3.g3 c6 4.Bg2 Nf6 5.0-0 Bd6 6.d4