I think you're right. I sort of knew there was something that didn't seem right about the fairness of this and you just nailed it.

<I would suggest that in future games where computer assistance is prohibited (probably too late for this one) that no exceptions are made to that rule regardless of the amount of integration between Opening Explorer and chess engines. >

Agreed 100%. I've been trying to think of some compromises, but none seem to work. As one example:

"After one side plays the first move not found in Opening Explorer, the other side may use engine analysis until the completion of their responding move."

I thought that'd be fair until it hit me that would be a bit unfair to the side that actually found a TN, in that the opposition would get an extra ply (and not incidentally, 2 more days) of analysis. So I wanted to amend that to:

"After one side plays the first move not found in Opening Explorer, both teams may use engine analysis until the completion of the other side's responding move."

A little better for the first team, but still not fair, as they might be left analyzing 6 possible replies while the second team can spend all their time and energy on engine analysis of the move they know will be played.

[Black "Mostertman Loek (NED)"]
[Result "1/2-1/2"]
[ECO "C57"] >

<1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 Bc5 5. Bxf7+ Ke7 6. Bc4 Rf8 7. O-O d6 8.Nc3 Qe8 9. Nd5+ Kd8 10. c3 h6 11. Nxf6 Rxf6 12. Nf3 Bg4 13. Be2 Bxf3 14. Bxf3>

54/75 +0.84 6. ... Qe8 7.Nc3 Nd4 8.d3 d6 9.Ne2 b5 10.Bb3 Qh5 11.Nxd4 Qxd1+ 12.Kxd1 Bxd4 13.Ke1 Rf8 14.Rf1 a5 15.a4 b4 16.Nf3 Ba7

53/79 +0.85 6. ... Qe8 7.0-0 d6 8.c3 Rf8 9.Nf3 Qg6 10.d4 Bb6 11.Qd3 Qxe4 12.Qxe4 Nxe4 13.a4 Be6 14.d5 Nxf2 15.Rxf2 Bf7 16.Bg5+ Ke8

<6...Rf8>

53/79 +1.05 6. ... Rf8 7.Nc3 h6 8.Nf3 d6 9.0-0 Qe8 10.Be2 Be6 11.d3 a5 12.Be3 Nd4 13.Bxd4 Bxd4 14.Nxd4 exd4 15.Nd5+ Bxd5 16.exd5 Kf7

<6...d6>

<Let's assume that this game proceeds 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Bxf7+ Ke7 6.b4 reaching the following position:

click for larger view

There is only one game in the database, M V Fiorito vs G Lambers, 1989. Does that mean that:

1. The position above is in Opening Explorer and therefore Team Black can analyze it using chess engines?>

Excellent question. At first I was tempted to say "No, that position is not in the Opening Explorer, because it terminates on that move." (If you go to the position in the Opening Explorer there is no link a page with 6.b4 played.) However, that's not actually true.

If the intention was to play Bxf2+, you can plug the FEN for that position into the homepage search you do indeed come up with this page Opening Explorer where premium members can request a Stockfish evaluation on demand.

So yes, if 6.b4 is played then computer analysis is still "on".

<2. The position following any move that Team Black makes leaves the Opening Explorer book and therefore Team White cannot analyze the position resulting from Black's 6th move using chess engines?>

For instance, if the play went 6.b4 Nxb5 then we truly would be out of the Opening Explorer, and the novelty would be 6...Nxb5. At this point I would declare on both forums that computer analysis is "off" and it turns into a Battle of the Brains from that point forward.

<3. The position following any move that Team Black makes <except> 6...Bxf2+ (which was Black's 6th move in the game above) cannot be analyzed using chess engines. But the position after 6...Bxf2+, which was the next move in the game referenced by Opening Explorer, is considered to be part of Opening Explorer and therefore can be analyzed by Team White using chess engines?>

Exactly. You can analyze the position after 6...Bxf2+ precisely because of the existence of this page: Opening Explorer. Even people not signed up to the game could request an analysis of that position; it would be impractical to prevent it considering that there's an button reading "engine" that will pull up analysis instantly if anybody clicks it. (I've meticulously avoided clicking it, but somebody reading my post probably will.)

<4. Therefore, by extension, any position arising from the moves M V Fiorito vs G Lambers, 1989 can be considered part of Opening Explorer and therefore can be analyzed using chess engines?

You can see my confusion based on possible interpretations of your instructions.>

Indeed I do see the confusion. Not every position from Fiorito vs Lambers is part of the Opening Explorer, and yet the novelty has not truly been made until a deviation is made from that game.

The "trick" I used to pull up the ...Bxf2 Opening Explorer page only works a few moves deep, then it stops. But what if you happen to follow Fiorito vs Lambers longer than the trick allows?

Let me try to restate the policy more specifically to cover this and similar cases:

"As soon as a position is reached which exists in no games in the Chessgames database (regardless of whether it's actually in the Opening Explorer) the site will declare to both teams that computer analysis is 'off' and no further computer analysis may be conducted by either team."

Note that it's very likely that the deviation from the Opening Explorer and the CG database will be the very same position, but it might not be, so the above statement is more accurate.

<Also, it seems to me that the team that had the opportunity to use chess engines in the position of the last move listed in Opening Explorer has an unfair advantage since it will know the other team's best response to that move (based on chess engine evaluations) and the ways to punish lesser responses, while the opposing team does not have that capability.>

I see your point. It's a little bit like what an adjournment would be like if we didn't have "sealed moves." One side gets to do immense computer analysis in preparation for the surprise they are about the spring, but the other side doesn't get to run to the engines to see the very same lines that the TN-springing team now has archived.

On the other hand, rewarding the team that springs the genuine TN doesn't seem too bad.

<I would suggest that in future games where computer assistance is prohibited (probably too late for this one) that no exceptions are made to that rule...>

I assume that the example line with 6.b4?! was picked precisely because that's a seemingly silly move, and an unlikely that either team is expecting to game to go in that direction.

<If you want me to, I can redact the specifics of 6.b4 and M V Fiorito vs G Lambers, but I'm hoping to just copy and paste my reply to keep both teams up to speed on this. Please advise.>

But maybe you should wait until my teammates have had a chance to concur before you share the information with Team White. I would hate to be considered the "traitor" that gave away our "secrets", even if I did it unintentionally!

1. Rf8 seems as a "classical" (book) choice, probably followed by d6 to free our second bishop.

♔

<All> I've been requested to clarify the somewhat unusual computer-use policy for this game. <Let's assume that this game proceeds 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Bxf7+ Ke7 6.b4 reaching the following position:

click for larger view

There is only one game in the database, M V Fiorito vs G Lambers, 1989. Does that mean that:

1. The position above is in Opening Explorer and therefore Team Black can analyze it using chess engines?>

Excellent question. At first I was tempted to say "No, that position is not in the Opening Explorer, because it terminates on that move." (If you go to the position in the Opening Explorer there is no link a page with 6.b4 played.) However, that's not actually true.

If the intention was to play Bxf2+, you can plug the FEN for that position into the homepage search you do indeed come up with this page Opening Explorer where premium members can request a Stockfish evaluation on demand.

So yes, if 6.b4 is played then computer analysis is still "on".

<2. The position following any move that Team Black makes leaves the Opening Explorer book and therefore Team White cannot analyze the position resulting from Black's 6th move using chess engines?>

For instance, if the play went 6.b4 Nxb5 then we truly would be out of the Opening Explorer, and the novelty would be 6...Nxb5. At this point I would declare on both forums that computer analysis is "off" and it turns into a Battle of the Brains from that point forward.

<3. The position following any move that Team Black makes <except> 6...Bxf2+ (which was Black's 6th move in the game above) cannot be analyzed using chess engines. But the position after 6...Bxf2+, which was the next move in the game referenced by Opening Explorer, is considered to be part of Opening Explorer and therefore can be analyzed by Team White using chess engines?>

Exactly. You can analyze the position after 6...Bxf2+ precisely because of the existence of this page: Opening Explorer. Even people not signed up to the game could request an analysis of that position; it would be impractical to prevent it considering that there's an button reading "engine" that will pull up analysis instantly if anybody clicks it. (I've meticulously avoided clicking it, but somebody reading my post probably will.)

<4. Therefore, by extension, any position arising from the moves M V Fiorito vs G Lambers, 1989 can be considered part of Opening Explorer and therefore can be analyzed using chess engines?

You can see my confusion based on possible interpretations of your instructions.>

Indeed I do see the confusion. Not every position from Fiorito vs Lambers is part of the Opening Explorer, and yet the novelty has not truly been made until a deviation is made from that game.

The "trick" I used to pull up the ...Bxf2 Opening Explorer only works a few moves deep, then it stops. But what if you happen to follow Fiorito vs Lambers longer than the trick allows?

Let me try to restate the policy more specifically to cover this and similar cases:

"As soon as a position is reached which exists in no games in the Chessgames database (regardless of whether it's actually in the Opening Explorer) the site will declare to both teams that computer analysis is 'off' and no further computer analysis may be conducted by either team."

Note that it's very likely that the deviation from the Opening Explorer and the CG database will be the very same position, but it might not be, so the above statement is more accurate.

<Also, it seems to me that the team that had the opportunity to use chess engines in the position of the last move listed in Opening Explorer has an unfair advantage since it will know the other team's best response to that move (based on chess engine evaluations) and the ways to punish lesser responses, while the opposing team does not have that capability.>

I see your point. It's a little bit like what an adjournment would be like if we didn't have "sealed moves." One side gets to do immense computer analysis in preparation for the surprise they are about the spring, but the other side doesn't get to run to the engines to see the very same lines that the TN-springing team now has archived.

On the other hand, rewarding the team that springs the genuine TN doesn't seem too bad.

<I would suggest that in future games where computer assistance is prohibited (probably too late for this one) that no exceptions are made to that rule...>

Well, I prefer 6...Qe8 and here is my reason why:

6. ... Qe8 7. Nf3 d6 8. O-O Rf8 9. c3 Qg6 10. d4 Bb6 11. Qd3 Qxe4 12. Qxe4 Nxe4 13. Re1 Nf6 14. a4

(14. dxe5 Nxe5 15. h3 Kd8 16. Nxe5 dxe5 17. Be3 Re8 18. Nd2 c6 19. Bg5 h6 20. Bh4 g5 21. Bg3 e4 22. Rad1 Bd7 23. Nb3 Kc8 24. Bf7 Re7 25. Bg6 e3 26. fxe3 Nd5 27. Kh2 Rxe3 28. Nd4 Rxe1 29. Rxe1 a5 30. Nf5 Nf4 31. Bxf4 gxf4 32. Nxh6 a4 33. Bf5 Ra5 34. Re8+ Bd8 35. Rf8 Rb5 36. b4 axb3 37. axb3 Bxf5 38. Nxf5 Rxb3 39. h4 Rxc3 40. h5 Rd3 41. h6 Rd7 42. Kg1 c5 43. Ng7 c4 44. h7 c3 45. Rxf4 Bb6+ 46. Kf1 Rd8 47. Rc4+ Kd7 48. Rxc3 Rh8 49. Rh3 Bd8 50. g3 Ke7 51. g4 Kf6 52. Nf5 Kg6 53. Nd6 Rxh7 54. Rxh7 Kxh7 55. Nxb7 Be7)

2. Qe8 is surely a good candidate, and we go out of the book, so no more Stockfish... Does d6 would follow? What's the plan from there?>

We will have a difficult time to hold them to a draw.

6. ... Qe8

(<7. Nc3> Rf8 8. O-O h6 9. Nd5+ Kd8 10. Nxf6 Rxf6 11. Nf3 Qg6 12. d4 exd4 13. e5 Rf8 14. Re1 d6 15. e6 Rf6 16. Qe2 Ne7 17. Bd2 a5 18. c3 d5 19. cxd4 Rxe6 20. Qf1 Bd6)

click for larger view

7.c3 Rf8 8. Nf3

(8. O-O d6 9. Nf3 Bb6 10. d3 Bg4)

8... Bb6 9. O-O d6 10. d4 Bg4 11. Be3 Bxf3 12. Qxf3 exd4 13. Bxd4 Nxd4 14. cxd4 Bxd4 15. Nd2 Qh5 16. Qxh5 Nxh5 17. Nf3 Be5 1/2-1/2

click for larger view

6...Qe8 7. O-O d6 8. c3

1 29 +1.13 8.... Bg4 9.Be2 Bxe2 10.Qxe2 Bb6 11.Nf3 Qh5 12.d3 h6 13.Kh1

2 29 +1.13 8.... Rf8 9.Nf3 Bb6 10.d4 Kd8 11.Bg5 Qg6 12.dxe5 Nxe5 13.Nbd2 Bg4 14.Nxe5 Qxg5 15.Nef3 Qf4 16.Bd3 Kc8 17.Qc2 Bxf3 18.Nxf3 c6

3 29 +1.15 8.... Bb6 9.d4 Bg4 10.f3 Bd7 11.f4 h6 12.Nf3 Kd8 13.fxe5 Nxe5 14.Be2 Nxe4 15.Nbd2 Nxd2 16.Bxd2 Rf8 17.Kh1 Nxf3 18.Bxf3 Kc8

4 29 +1.41 8.... Qh5 9.Nf3 Ng4 10.d4 exd4 11.Bf4 Nxf2 12.Rxf2 dxc3 13.b3 Bxf2+ 14.Kxf2

6...Rf8 7. O-O d6 8. Nc3

1 29 +1.33 8.... Qe8 9.Nd5+ Kd8 10.c3

2 29 +1.71 8.... Ke8 9.d4 exd4 10.Na4 Bg4 11.f3

3 28 +1.95 8.... Nb4 9.Ne2 Nc6 10.Ng3 h6 11.Nf3 Bg4 12.c3 Qd7 13.b4 Bb6 14.d3 Nh5 15.Nf5+ Rxf5 16.exf5 Qxf5 17.a4 a6 18.Be3 Bxf3

4 28 +2.36 8.... h6 9.Nh7 Nxh7 10.Nd5+ Ke8 11.Qh5+ Rf7 12.Nb6 Ng5 13.Bxf7+ Nxf7 14.Nxa8 Bd7 15.Nxc7+ Qxc7 16.d3 Nd8 17.Kh1 g5 18.c3 Ne6

6...Rf8 7. O-O d6 8. Nc3 Qe8 9.Nd5+ Kd8 10.c3

1 30 +1.33 10.... h6 11.Nf3 Bb6 12.Nxf6 Rxf6 13.Bd5 Bg4

2 30 +1.57 10.... Bb6 11.d4 exd4 12.cxd4 h6 13.Nxf6 gxf6 14.Nf3

3 29 +1.89 10.... Qg6 11.Nxf6 gxf6 12.Ne6+ Bxe6 13.Bxe6 Qxe4 14.b4 Bb6 15.a4 a6 16.Re1 Qg6 17.Bd5 Re8 18.d3 Kd7 19.Bd2 Rab8 20.Qf3 f5

4 29 +1.95 10.... a5 11.d4 exd4 12.Nf4 dxc3 13.Nfe6+ Bxe6 14.Nxe6+ Kc8 15.Nxf8 cxb2 16.Bxb2 Qxf8 17.Kh1 Qe7 18.f3 Ne5 19.Be2 a4 20.Qd2 a3

6...Rf8 7. O-O d6 8. Nc3 Qe8 9.Nd5+ Kd8 10.c3 h6 11.Nf3

1 37 +1.43 11.... Bg4 12.Nxf6 Rxf6 13.Be2 a5 14.d3 Bd7 15.Be3 Bxe3 16.fxe3 Kc8 17.Nh4 Rxf1+ 18.Qxf1 a4 19.Qf3 b6 20.Nf5 Qg6 21.Qg4 Qxg4

2 36 +1.39 11.... Bb6 12.Nxf6 Rxf6 13.Be2 Ke7 14.d4 Kf8 15.d5 Ne7 16.Nd2 Ng6 17.Nc4 Qf7 18.Bf3 Kg8 19.a4 Bh3 20.Nxb6 axb6 21.Bh5 Bc8

3 36 +1.61 11.... Bd7 12.d4 Bb6 13.Nxb6 axb6 14.dxe5 Nxe5 15.Nxe5 Qxe5 16.f3 Bb5 17.Bxb5 Qxb5 18.Re1 Nd7 19.b3 Kc8 20.a4 Qh5 21.c4 Qg6

4 36 +1.63 11.... a5 12.d4 Ba7 13.Be3 Bg4 14.Nxf6 Rxf6 15.Be2 exd4 16.Nxd4 Bxe2 17.Qxe2 Bxd4 18.Bxd4 Re6 19.f3 g5 20.Qc4 Kc8 21.Qd5 Ra6

6...Na5 7.Be2

1 35 +1.71 7.... Nc6 8.O-O d6 9.c3 Bb6 10.d3 h6 11.Nf3 Re8 12.b4 Kf8 13.Nbd2 Be6 14.Bb2 a6 15.d4 Bd7 16.d5 Ne7 17.c4 Ng6 18.Re1 Kg8 19.Qc2 Qe7

2 35 +1.71 7.... d6 8.O-O Bb6 9.d3 h6 10.Nf3 Nc6 11.Nbd2 Be6 12.c3 Re8 13.b4 Kf8 14.Bb2 a6 15.d4 Bd7 16.d5 Ne7 17.c4 Ng6 18.Re1 Kg8 19.Qc2 Qe7

3 35 +1.71 7.... h6 8.Nf3 d6 9.O-O Re8 10.c3 Bb6 11.b4 Nc6 12.d3 Kf8 13.Nbd2 Be6 14.Bb2 a6 15.d4 Bd7 16.d5 Ne7 17.c4 Ng6 18.Re1 Kg8 19.Qc2 Qe7

4 35 +1.83 7.... Bb6 8.Nc3 Nc6 9.Nd5+ Kf8 10.d3 h6 11.Nf3 d6 12.O-O Kg8 13.a4 Be6 14.Nxb6 axb6 15.Be3 Qe8

6...Qf8 O-O

1 30 +1.61 7.... d6 8.c3 Bg4 9.Be2 Bxe2 10.Qxe2 a6 11.Nf3 Ba7 12.Rd1 Re8 13.d4 exd4 14.cxd4 Kd8 15.Nc3 Kc8 16.d5 Ne5 17.Nxe5 dxe5

2 30 +2.28 7.... Bb6 8.Nc3 d6 9.Nd5+ Nxd5 10.exd5 Nd4 11.Kh1 h6 12.Ne4 Nf5 13.f4 exf4 14.Rxf4 Kd8 15.c3 Qe7 16.d3 a5 17.Qe2 g5

3 29 +2.32 7.... Qe8 8.Nc3 Rf8 9.Nd5+ Kd8 10.Nxf6 gxf6 11.d4 exd4 12.Nxh7 Rh8 13.Nxf6 Qe5 14.Ng4 Qg7 15.h3 d6 16.Bf4 Bd7 17.Be2 Ne5

4 29 +2.38 7.... Na5 8.Be2 Nc6 9.c3 h6 10.Nf3 Nxe4 11.d4 exd4 12.b4 Bd6 13.b5 Ne5 14.Nxe5 Bxe5 15.cxd4 Bd6 16.Qd3 Ng5 17.Nc3 Kd8

6...d6 7.Nc3 Qf8 8.O-O

1 33 +1.39 8.... Bg4 9.Nd5+ Kd8 10.Be2 Bd7 11.d3 Nd4 12.Be3 Kc8 13.c3 Nxe2+ 14.Qxe2 Bb6 15.a4 Bxe3 16.fxe3 c6 17.Nxf6 gxf6 18.Qf2 h6

2 33 +1.41 8.... h6 9.Nf3 Bg4 10.Be2 Qf7 11.d3 Bb6 12.Bd2 Rhe8 13.Be3 Kf8 14.Nh4 Bxe2 15.Qxe2 Kg8 16.Qd1 Rf8 17.Nf5 Ne7 18.a4 Nxf5

3 32 +1.85 8.... Na5 9.Be2 Nc6 10.d3 Nd4 11.Nd5+ Kd8 12.Bh5 g6 13.c3 gxh5 14.cxd4 Bxd4 15.Nxf6 Qxf6 16.Qxh5 Kd7 17.Be3 Qg6 18.Qh4 Rg8

4 32 +2.06 8.... Nd4 9.Kh1 Ke8 10.Nf7 Rg8 11.d3 Be6 12.Bxe6 Nxe6 13.Ng5 Nxg5 14.Bxg5 h6 15.Bxf6 gxf6 16.f4 Qg7 17.Qh5+ Kd8 18.g3 c6

6...Qe8 7.O-O h6 8.Nf3 d6 9.Nc3

1 33 +1.11 9.... Kd8 10.Be2 Nd4 11.Nxd4 exd4 12.Nd5 Nxd5 13.exd5 Qe5 14.d3 Qxd5 15.Bf3 Qf5 16.Bd2 a5 17.c4 Re8 18.Qc2 Bb4 19.Rfe1 c6

2 32 +1.19 9.... Qh5 10.Be2 Bg4 11.Rb1 Raf8 12.b4 Nxb4 13.d3 Qe8 14.Be3 Bxf3 15.Bxf3 b6 16.Bxc5 dxc5 17.Nd5+ Nbxd5 18.exd5 Kf7 19.Re1 Qd7

3 32 +1.19 9.... Bg4 10.Be2 Qh5 11.Rb1 Raf8 12.b4 Nxb4 13.d3 Qe8 14.Be3 Bxf3 15.Bxf3 b6 16.Bxc5 dxc5 17.Nd5+ Nbxd5 18.exd5 Kf7 19.Re1 Qd7

4 32 +1.19 9.... Rf8 10.Be2 Qg6 11.d3 Nd4 12.Nxd4 Bxd4 13.Bf3 Be6 14.Nd5+ Bxd5 15.exd5 Kf7 16.Bd2 Kg8 17.c3 Bb6 18.Qe2 Rae8 19.Rae1 Qf7

6..Qe8 7.Nc3 Nd4 8.d3

1 31 +0.86 8.... d6 9.Ne2 b5 10.Bb3 Nxb3 11.axb3 Rf8 12.Nf3 Kf7 13.Be3 Bxe3 14.fxe3 b4 15.O-O a5 16.Ng3 Kg8 17.h3 Bd7

2 31 +1.53 8.... h6 9.Nf3 Qh5 10.Be3 d5 11.exd5 Bg4 12.Bxd4 exd4 13.Ne4 Bxf3 14.Qxf3 Qxf3 15.gxf3 Bd6 16.Ke2 Rhe8 17.h4 Nh5

3 30 +1.55 8.... Rf8 9.O-O h6 10.Nf3 d6 11.Nxd4 Bxd4 12.Be3 Bxe3 13.fxe3 Kd8 14.d4 Bd7 15.Be2 a5 16.a4 Kc8 17.Qe1 c6