VikingForce wrote on 01/15/10 at 13:31:01:


Having played the Breyer as my main defence for eight years now, I face 15.b3 roughly as frequently as 15.a4. Right now, as the other posters have noted, Black seems fine against 15.b3, so 15.a4 looks more challenging at the moment. A small innovation for White in the 15.b3 line, or for Black in the 15.a4 line, may be enough to change that evaluation.

I remember Leko's instructive win over Beliavsky back in 2002 (with 15.b3) causing some people to claim that Leko had refuted the Breyer. One year later, I was asked by a surprised spectator why I played the Breyer, saying something like "don't you know about Leko's 15.b3?" Later on, Black found new resources, and suddenly 15.b3 wasn't dangerous anymore. Evaluations change, and with them the popularity of the different lines. Still, we are talking about very small changes, which people tend to blow up into statements like "the Breyer is refuted." If you prefer 15.b3 to 15.a4, I'd say: Play it!

Daniel wrote on 01/15/10 at 17:53:54:


15.b3 became quite popular as White found resources against Black's response 15...d5 that made the line look good for awhile.  I think Black has managed to equalize here.  Later, though, Black found that 15...Rc8 was an even better option, and Black's game looks fairly straightforward here.  This is the line that seems to have put 15.b3 on the shelf for the moment.  I seem to recall that Short played a very instructive game with the Black pieces that shows how to combat White's attempts.

Daniel wrote on 01/15/10 at 17:53:54:


I saw some of them and it looks acceptable for black.

look at avrukh games.  His method with Rc8, Nb6, and c6 seems quite acceptable for black.