🚀 go-pugleaf

What I am aiming for is a format for a position database in a hash table
where the move element is sufficient to compute the hash code of the next
position when only the hash code of the current position is known. This
would allow utility programs the follow the links from any entry within
the hash table.

I counted all the legal moves for each piece, starting square, destination
square, captures, promotions, enpassant and changes to castling. This is
all the information necessary to determine the change in the position hash
code. I want to aviod variable length fields so I'm not going into
statistical encoding either.

In article <bud%4.561$Ea1.52002@carnaval.risq.qc.ca>, "philippe"
<boucherp@geocities.com> wrote:
> If you want compression, there is much more compression than that.  Simply
> refer to the n th legal move, according to a specific ordening order
> algorithm that you'll use. You can then add special control codes by using
> the nth +1 (non-legal) move to stop a line and do whatever you want.
> 
> There is also way to optimize that by using stats and computijng power, but
> I'll not enter in the details ;-)

If you used an evaluator to order the moves then most of the interesting
moves would be at the front of the list and you would only need a couple
of bits to indicate if the move is good or bad. Most moves would be
implied by the index and require 0 bits to encode. I don't think you could
beat this but it is only suitable for a static table. I need to build the
dynamic table first to collect the data that would go into the static
table.


> "Dan O." <oetting@ghtmail.cr.usgs.gov> a �crit dans le message news:
> oetting-3105000920120001@gldppp94.cr.usgs.gov...
> > By my count, there are exactly 22,075 legal chess moves that fully
> > describe the change to the chess board state including captures,
> > promotions and castle availability. I would like to encode these moves in
> > a 15 bit field for an opening book. Is there already a compact move
> > encoding that specifies the complete move without reference to the current
> > board?
> >
> > --
> > Dan Oetting <oetting@ghtmail.cr.usgs.gov>

-- 
Dan Oetting <oetting@ghtmail.cr.usgs.gov>