Question to French

Aye, also if Black doesn't do something, White will play b4 himself, which would be favourable.

White wants to expand on the queenside, inhibiting black's play there. Also, it is a good way to bring the black-squared bishop to b2, defending the d4 pawn.

a3 prevents Black from checking on b4, which, like BorgQueen mentioned, is common after cxd4, cxd4.  But this also allows Black to play ...c4.

Against this a3 line in the advance variation I tend to continue....

I play the Qb6 variation against the advance.  Try this line.

RainbowRising,

I made the same mistake, look again at what Eric said, Nxe5 not d4.  Damn this algebraic notation.  Only descriptive makes any sense to me.  If Bxd7 Nxd7, not Qxd7.

Nxe5 is quite a common idea in the Bd7 variations of the advance. For example I can't tell you how many times I've won a pawn like this.

I know the Nxe5 motif, my mind just did the usual half translation of algebraic and descriptive.  The mistakes I make transferring moves from my opening books, especially when I'm playing a new opening, are often horrendous.

Hi there!

Please be aware of the aim of black play. Pressure on d4 with the c5 pawn. Playing a3 is a way to threaten b4 and to force black to take a decision about the c5 pawn, releasing the pressure on the white center.

Moreover, the Bishop can go to b2 protecting the center another time and freeing the dveloppement of the white queenside.

I hope that helps