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Subject: Re: The Code for the Rybka-Mate-Bug

Author: Steve Maughan

Date: 01:44:15 12/14/05

Go up one level in this thread


Vasik,

>The problem is when the hash entry ages.

This is easy to get around - just store the distance to mate from the *position*
(i.e. not the root) in the hash table.

In pseudo code:

procedure push_hash(position)
begin
	if winning_mate_value_in_hash then
		hash_draft_depth += position's_ply_from_root
	else if losing_mate_value_in_hash then
		hash_draft_depth -= position's_ply_from_root
	store(position)
end;

procedure probe_hash(position)
begin
	if found_in_table(poistion) then
	begin
		get_hash(position)
		if winning_mate_value_in_hash then
			hash_draft_depth -= position's_ply_from_root
		else if losing_mate_value_in_hash then
			hash_draft_depth += position's_ply_from_root
	end
end;

I hope this helps!

Regards,

Steve



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