Martin Brown wrote:

Apologies for following up my own post but the engine is still running
and at ply 20 after 3 hours the results are looking increasingly like
the conventional wisdom. Namely

0.79 Nf3
0.79 Be2
0.71 Bg5
0.61 Be3
0.60 e5
0.59 Bf4

(AFAIK Bf4 has not been played so is a potential novelty here)

At 18 ply it prefers 5. Nf3 0.84 then 5. Be2 0.84 with 5. e5 0.78
trailing and the same order occurs at ply 19 after an hour.

How deep did you let Rybka go?

Rather than see this as White's center quick-
ly collapsing (as described by one fellow here),
Rybka sees it as merely trading one advantage
for another. Without p-f4, White's massive
wall of central pawns must collapse.

Matches where 5. e5 have been played have not generally gone well for
white. The popular choices yield 60% score (vs 35% for e5). As a pure
curiosity 5. g5 manages 100% out of just 2 games played.

g5 is well down the list now. Scoring 0.17 and ranked 23/47

Regards,
Martin Brown