beowulf opening book

[EricLang]

I was playing around with openingbooks and downloaded the biggest from the Beowulf site:

Code: Select all

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq -
d2d4{66543} c2c4{15464} e2e4{56484} b2b3{190} g1f3{17667} g2g3{701} c2c3{10} b1c3{31} b2b4{20} f2f4{23}
rnbqkbnr/pppppppp/8/8/3P4/8/PPP1PPPP/RNBQKBNR b KQkq d3
g8f6{39159} g7g6{406} d7d5{11933} f7f5{983} c7c5{96} d7d6{1388} e7e6{2094} b7b5{10} b7b6{10} b8c6{21} c7c6{11}

Here we see at the second position "d3" as enpassant square???
Can anyone understand this?
I guess the line after the position indicates the moves and the number of times it has been played between "{' and "}"?

[Ron Murawski]

I was playing around with openingbooks and downloaded the biggest from the Beowulf site:

Code: Select all

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq -
d2d4{66543} c2c4{15464} e2e4{56484} b2b3{190} g1f3{17667} g2g3{701} c2c3{10} b1c3{31} b2b4{20} f2f4{23}
rnbqkbnr/pppppppp/8/8/3P4/8/PPP1PPPP/RNBQKBNR b KQkq d3
g8f6{39159} g7g6{406} d7d5{11933} f7f5{983} c7c5{96} d7d6{1388} e7e6{2094} b7b5{10} b7b6{10} b8c6{21} c7c6{11}

Here we see at the second position "d3" as enpassant square???
Can anyone understand this?
I guess the line after the position indicates the moves and the number of times it has been played between "{' and "}"?

You have understood perfectly. The first line is the FEN position with side-to-move, castling rights (if any) and ep square (if any); the 2nd line is each associated move in algebraic notation followed by the number of times the move was played from that position. Additionally there's an '#END#' tag at the end of the book.

Ron

[michiguel]

I was playing around with openingbooks and downloaded the biggest from the Beowulf site:

Code: Select all

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq -
d2d4{66543} c2c4{15464} e2e4{56484} b2b3{190} g1f3{17667} g2g3{701} c2c3{10} b1c3{31} b2b4{20} f2f4{23}
rnbqkbnr/pppppppp/8/8/3P4/8/PPP1PPPP/RNBQKBNR b KQkq d3
g8f6{39159} g7g6{406} d7d5{11933} f7f5{983} c7c5{96} d7d6{1388} e7e6{2094} b7b5{10} b7b6{10} b8c6{21} c7c6{11}

Here we see at the second position "d3" as enpassant square???

Correct. That is what the EPD standard requires after you move 1.d4, even if there is no black pawn in c4 or e4.
For the EPD standard, enpassant square does not mean there is a valid capture in d3, it means white just played d4. It is up to the engines to figure out the legal possibility of an ep capture.

Miguel

Can anyone understand this?
I guess the line after the position indicates the moves and the number of times it has been played between "{' and "}"?

[EricLang]

Ok. I was wandering about the non-existing ep-square. But I saw on Wiki it always the square behind a double pawn move, if there is any

[EricLang]

Isn't it just a wrong fen-specification? Why on earth should we set the enpassant-square if there is no enpassantcapture possible?
In my opinion we should just set it when there really is an ep-capture possible.

[grant]

I found this on the web.

An en passant target square is given if and only if the last move was a pawn advance of two squares. Therefore, an en passant target square field may have a square name even if there is no pawn of the opposing side that may immediately execute the en passant capture.

Though it does seem pointless if there is no opposing pawn.

Grant

[Ron Murawski]

I have found no single opening book position where both an ep capture plus a different move are in my book. This means that for an opening book position, the ep square does not matter at all! Ed Schroeder has also said the same.

In the future I will be experimenting by eliminating the 'ep-ness' of opening book positions (thus reducing the book size) and see if the engine gets bitten. This project is not very high in my to-do list and may never be performed! Has anyone else tried this idea?

Ron