On Apr 19, 4:47*pm, help bot wrote:
On Apr 19, 10:53 am, help bot wrote:

1. e2-e4{0} e7-e5{2}
2. Ng1-f3{0} Nb8-c6{2}
3. Bf1-b5{0} a7-a6{2}
4. Bb5-a4{0} Ng8-f6{2}
5. Ke1-g1{48} Bf8-e7{4}
6. d2-d3{20} Ke8-g8{16}

Although 7. BxN dxB 8. Nxe5 snaffles a pawn it isn't such a massive
advantage. However, since it is a purely materialistic gain it is
surprising that Getclub did not grab it with both hands.

I take that back. I had been assuming (incorrectly) that if it was a
significant advantage to white that blundercheck would have added the
relevant annotation. But since it didn't... I assumed there was
something about it that I couldn't quite see.

However, it seems looking more carefully at the opening book database
move order 7. BxN is the *only* continuation given at that point. The
game falls back into book territory further on by transposition.

A proper ab initio analysis of this position with Shredder quickly
concludes that BxN is 60cp better than the next best move Nc3, c4, h3,
Bd2 (all at 0 +/-3). Rybka is a bit more conservative and gives a 40cp
advantage with a preferred ordering of toher moves h3, Bd2, c4, Nc3,
Bb3a3, Bg5, Re1 (all at 6+/-2).

Rybka typically has a flatter evaluation function (like Fritz and
Crafty). Shredder has an exaggerated sense of some structural features
(which I think tends to guide it towards more human like play).

* After thinking about this a little more, I realized
that the Knight need not be snatched before
taking the pawn, since it is, after all, pinned to
the King.

* Whoa! *Taking it just a tad slower, I now see that
5. Ke1-g1 *is* castling, so the a1-e8 pin is no more.

Oops. I really wish he would fix the £$#^$&% useless game notation. I
find that the captures being shown as ordinary moves make life all but
impossible for following the games without a board or a computer.

* Now that I have the old 'puter freed up, I see that:

at zero seconds, it likes 6. Bxc6!
at one second, ditto
at two minutes, the same
at eleven minutes, it still prefers Bxc6!

And after an overnight analysis to ply 23 it is still the same only a
slightly larger advantage crystallises.

* Black has nothing for the pawn-- except what I
suppose could euphemistically be termed "open
lines"; the same open lines you get when you
hang a piece which was obstructing your other
pieces... .

* If Black has any plans of getting some real
compensation for hanging a center pawn in the
Ruy Lopez, he's better off with the Marshall
Gambit, IMO.

The problem is that I used blundercheck and trusted it to annotate any
dumb moves. Since it didn't annotate this I assumed incorrectly that
it was sound (and inside the usually robust book horizon). I confess I
didn't lok very hard at first.

The flaw is that when a move that is out of book is played (ie but the
wrong order) blundercheck should run the engine and see if the
sequence order alters the outcome significantly. Hitting a position
that is in the opening book repertoire is not a sufficient test -
there should be an option to cross check all the opening moves too
(especially any where the move played is not on the approved book list
for that ply - played out of order).

I have noticed blundercheck sometimes misses clearly winning lines
when used to annotate certain types of game. I presume it stems from
having the cache polluted with moves from the suboptimal line actually
played when the decsisive move is encountered in the backwards search
down the tree.

Regards,
Martin Brown