Introducing the *.EBF project

[flok]

Personally, I think it wise to store every pv node an engine ever finds in a file. Load the file on startup. Whenever a new pv node is found or any pv node is improved, update the file.

Let's call it permanent pv hash.
That is another kind of book information.
Pv nodes are rare, and therefore valuable.

Funny you bring that up. I was just considering implementing my mini-Shogi book in Shokidoki that way.

What is a PV node? What I think a pv is, is the list of moves from root to the leave of the ideal exchange of moves. Are those the PV nodes? Or?

[Dann Corbit]

Personally, I think it wise to store every pv node an engine ever finds in a file. Load the file on startup. Whenever a new pv node is found or any pv node is improved, update the file.

Let's call it permanent pv hash.
That is another kind of book information.
Pv nodes are rare, and therefore valuable.

Funny you bring that up. I was just considering implementing my mini-Shogi book in Shokidoki that way.

What is a PV node? What I think a pv is, is the list of moves from root to the leave of the ideal exchange of moves. Are those the PV nodes? Or?

A pv node is a principal variation node.
It is one of the moves in the sequence that the engine intends to play.
https://chessprogramming.wikispaces.com ... +variation

[flok]

A pv node is a principal variation node.
It is one of the moves in the sequence that the engine intends to play.
https://chessprogramming.wikispaces.com ... +variation

Ok but why can we have multiple?

[PK]

In Rodent there is an option to record scores and depths for root positions, to retrieve them deeper in the search. I do not use it much, because every change renders these data useless, but toying with it for a few days shown some convergence with human book lines. Once it learned to avoid Alechine and to play Petroff, the other time I wanted it to learn to avoid some dubious line in QGD, but it kept shuffling between 1.d4 d5, 1.d4 Nf6 and 1.d4 e6 instead.

[Evert]

What is a PV node? What I think a pv is, is the list of moves from root to the leave of the ideal exchange of moves. Are those the PV nodes? Or?

Typically, a "node" is a position that is reached after a move. A PV-node is a node that is reached after making a move that is in the PV. The term is also commonly used for moves that are searched with an open (alpha != beta-1) window in a PVS search (technically, those would be "expected PV nodes").

[hgm]

In this context a PV node is just a node for which you have an exact score, rather than a bound.

[Dann Corbit]

I suggest storing them in sets according to material signature.

[Rebel]

First contribution is in by our member Folkert, embla.ebf

http://rebel13.nl/misc/ebf/

[Robert Pope]

The goal of this project is to create an extended opening book (or multiple books) for all chess engines that roughly will ensure:

Book hits for the first 10 plies with a 90-95% security
Book hits for the first 15 plies with a 75-80% security
Book hits for the first 20 plies with a 50-55% security
Book hits for the first 25 plies with a 25-30% security
Book hits for the first 30 plies with a 10-15% security.

If these numbers are feasible has to be seen, we are going to try it anyway.

What do you mean by "security"? Just that the book is wide enough that it will find a move X% of the time at that ply?

[Rebel]

Yep.