ECO-codes? openings?

[flok]

Hi,

While going through those statistics I generated on chess I looked into those ECO-codes. According to wikipedia (http://en.wikipedia.org/wiki/List_of_chess_openings) A00 is for example a3 but also a4 and c3 and A95 as well! So what is it? What does A00 etc. mean?

[Dann Corbit]

Hi,

While going through those statistics I generated on chess I looked into those ECO-codes. According to wikipedia (http://en.wikipedia.org/wiki/List_of_chess_openings) A00 is for example a3 but also a4 and c3 and A95 as well! So what is it? What does A00 etc. mean?

Here is a big list of chess openings categoried to the variant:
http://cap.connx.com/chess-engines/new- ... co.pgn.bz2

Games that have been categorized by this method are found here"
http://cap.connx.com/a-openings/
http://cap.connx.com/b-openings/
http://cap.connx.com/c-openings/
http://cap.connx.com/d-openings/
http://cap.connx.com/e-openings/

For instance:
http://cap.connx.com/a-openings/A00p.pgn.bz2
contains games that start out:
1. b4 e5 2. Bb2 Bxb4 3. Bxe5 Nf6 4. c4 O-O 5. e3 *

[flok]

Hi,

Thank you but that's not entirely what I meant. I meant: are all a3, a4 and c3 all A00 openings? Since they're also A95? If I want to use opening A00, what move should I do?

[adams161]

my understanding is A0 is openings of the form of like A01 A02 etc that dont fall into a more specific opening.

i.e. if your base opening is e4 c5 nf3 d5 [variants ]

the ones that dont fall ino the more specific category but do have the basic form fall into the 0.

Mike

[adams161]

sorry meant A00. A0 obviously is the sum of A00 through A09

[Dann Corbit]

Hi,

Thank you but that's not entirely what I meant. I meant: are all a3, a4 and c3 all A00 openings? Since they're also A95? If I want to use opening A00, what move should I do?

A00 means an irregular opening (there are lots of different kinds, including some of my favorites A00p-A00s).

Maybe this can help:
http://en.wikipedia.org/wiki/Encyclopae ... s_Openings
http://www.markalowery.net/Chess/ECO-Li ... ation.html

Generally, you can't track an opening from its earliest moves properly, because they can transpose into other openings.

For instance I have lots of games that start with:
1. b4 ...
Which would normally be some kind of orangutan game but transpose into something else such as:
A05
A06
A11
A15
A40
A55
A85
B20
B55
B61
B70f
B83
B84
B99e
B99h
C15b
C51
C69e
C80s
C89
D13/11
D18d
D23l
D48
D57
D94
E05o
E12x
E19
E91n
E94u

[Gerd Isenberg]

One issue with opening classifications like ECO, do they depend on determinant move sequences or determinant positions or unique features of a position? There are for instance transpositions, like caro-kann panov variation often transposes to QG (and vice versa). Would one call an e4-opening queens gambit?

[Eelco de Groot]

One issue with opening classifications like ECO, do they depend on determinant move sequences or determinant positions or unique features of a position? There are for instance transpositions, like caro-kann panov variation often transposes to QG (and vice versa). Would one call an e4-opening queens gambit?

I think that most opening classifications depend on a set of key positions, the last key position reached in a game determines the classification. A certain degree of ambiguity will always be involved like in the case of Dann's example, if a 1.b4 game evolves into a well known line of a traditional opening it makes more sense to classify it there. If the Queen's Gambit keyposition was first, -first as in belonging to an older system, but last keyposition reached in the game-, that will take precedence over a possible classification as a Caro-Kann. But if the system becomes more fashionable as a Caro-Kann than as a Queen's Gambit, the classification may be changed by the opening key designers when they make a new key.

With evolving theory you may want to upgrade your set of keypositions to make distinctions possible between different systems arising after an older keyposition that was in use closer to the root. Systems that are no longer fashionable may be downgraded to limit the number of positions in your key, and systems that are later played with a different moveorder may occasionally shift from one opening to a new opening classification this way, just like in dinosaur taxonomy new finds may occasionally lead to new classifications when better data has become available.

I think the main usefullness for the opening numbers is for human memory and a link to the traditional opening names, but does not have to used directly for searching purposes, the database just substitutes every opening number with a corresponding keyposition it can search in the database.

Regards, Eelco

[Gerd Isenberg]

One issue with opening classifications like ECO, do they depend on determinant move sequences or determinant positions or unique features of a position? There are for instance transpositions, like caro-kann panov variation often transposes to QG (and vice versa). Would one call an e4-opening queens gambit?

I think that most opening classifications depend on a set of key positions, the last key position reached in a game determines the classification. A certain degree of ambiguity will always be involved like in the case of Dann's example, if a 1.b4 game evolves into a well known line of a traditional opening it makes more sense to classify it there. If the Queen's Gambit keyposition was first, -first as in belonging to an older system, but last keyposition reached in the game-, that will take precedence over a possible classification as a Caro-Kann. But if the system becomes more fashionable as a Caro-Kann than as a Queen's Gambit, the classification may be changed by the opening key designers when they make a new key.

With evolving theory you may want to upgrade your set of keypositions to make distinctions possible between different systems arising after an older keyposition that was in use closer to the root. Systems that are no longer fashionable may be downgraded to limit the number of positions in your key, and systems that are later played with a different moveorder may occasionally shift from one opening to a new opening classification this way, just like in dinosaur taxonomy new finds may occasionally lead to new classifications when better data has become available.

I think the main usefullness for the opening numbers is for human memory and a link to the traditional opening names, but does not have to used directly for searching purposes, the database just substitutes every opening number with a corresponding keyposition it can search in the database.

Regards, Eelco

Yes, inside my program, I use zobrist keys to index the opening book containing lines with ECO-codes. I also used mirrored keys for white and black mirrored openings. I was surprised, how often transpositions regularly appear, specially from A05 or A06 iirc (dutch system) from/to sicilian and from 1. c4 e5, where white loses a tempo to transpose into a mirrored sicilian.

Is it a coincidence that B14 transposes to D41?

Code: Select all

[Event "opening"]
[Site "B14"]
[Date "2008.10.28"]
[Round "1"]
[White "W"]
[Black "B"]
[Result "*"]

1. e4 c6 2. d4 d5 3. exd5 cxd5 4. c4 Nf6 5. Nc3 e6 6. Nf3 Be7
7. cxd5 Nxd5 8. Bc4 Nc6 9. O-O *


[Event "opening"]
[Site "D41"]
[Date "2008.10.28"]
[Round "2"]
[White "W"]
[Black "B"]
[Result "*"]

1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Nf3 c5 5. cxd5 Nxd5 6. e3 Nc6
7. Bc4 cxd4 8. exd4 Be7 9. O-O *

Probably it makes sense to specify two ECO-codes in such cases.

Cheers,
Gerd