always same opening problem

[tatagi]

hello.

An engine I most frequently use always starts with nf3 when it is white

is it programmed that way or any other reason?


https://imgur.com/a/7vqHAPZ


btw it's fruit 2.1

[H.G.Muller]

Most engines play quite deterministically; they are not programmed to vary their move, but always play the move they think best. What they think is best can change as they think longer, so timing variations (through other tasks on your computer stealing CPU time) occasionally lead to a different move. This effect is larger with engines that use multiple cores (which Fruit 2.1 doesn't).

For variation you would have to make the engine use an opening book, rather than having it think up its own moves. Or have the GUI use one on the engine's behalve.

[peter]

Hi!

For variation you would have to make the engine use an opening book, rather than having it think up its own moves. Or have the GUI use one on the engine's behalve.

Sorry for hitchhiking the thread instead of opening a new one, but I'm very unexperienced with the program and don't want to make too much noise here all at once
How can I add single games to an existing .bin book used by the "Common Engine" by option.
I made it to create a new book but don't find a way to add games without overwriting the whole book with already many games within now, which a message tells me I'd do by "Save Games to Book" when the existing book is loaded.

Thanks in advance regards

[H.G.Muller]

I don't think this is currently possible, and I also do not see why it would be useful. Books are normally made from hundreds of thousands of games, so one game more will not make a difference. Furthermore, books are usually made from a collection of PGN games. People that want to add more games woul just add those games to the PGN file, and then redo the 'Save Games to Book' function for the total.

Adding just a few games will not have any impact on positions that already were visited a lot; they can have at most an effect near the leaves of the opening tree. But if you want to change the behavior there, you might as well put in the desired move (or alter the weight of an existing move) by hand, using the Edit Book function in that position.

There furthermore is a 'book learn' mode. This would alter the relative probabilities of book moves based on how often they where played and with which result. This can have significant effect on the playing frequencies even with only few games. (It would not add new moves to the book, though.)

[peter]

Adding just a few games will not have any impact on positions that already were visited a lot; they can have at most an effect near the leaves of the opening tree.

Thanks for the answer!
Of course single games played later on with an already finished book don't matter much at postitions with many games stored, they do more as for seldomly played ones.
And some kind of merging books could be useful now and then and adding bigger amounts of games later on too.

Yet I already thought by myself It wouldn't work that way, just wanted to be sure.

Thanks again regards

[H.G.Muller]

There exist command-line utilities that can merge books, e.g. Polyglot. So it did not seem necessary to put too much of this functionality in XBoard. The main reason for having these book functions in XBoard was to also provide them for Chess variants. (Polyglot can handle orthodox Chess only. But that only hampers it in conversion from games to book; merging books should work in any variant, as it would not have any idea what the positions are, as the hash keys cannot be inverted to positions.) And where they would have to be interactive, such as in book editing.