Integrated Bounds and Values
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Integrated Bounds and Values (IBV) were proposed 1995 by Don Beal [1]. It treats values and bound flags, typically stored as distinct items inside a transposition table, inside one scalar value as a single numeric scale, providing a convenient notion for coding and processing backed-up values, and might slightly simplify control structure for storing and retrieving TT scores.
IBV in Alpha-Beta
Inside an alpha-beta search, for a beta-cutoff one has to compare with forceExact(beta), to return forceLB in that case.
int ibvSearch(int alpha, int beta, ...) {
...
int cut = forceExact(beta);
for (all moves) {
...
score = -ibvSearch(-beta, -alpha, ...);
...
if ( score >= cut )
return forceLB(score);
...
}
...
}
with
int forceExact(int x) {return (x+1) &~ 3;}
int forceLB (int x) {return forceExact(x) + 1;}
Publications
- Don Beal (1995). An Integrated-Bounds-and-Values (IBV) Numeric Scale for Minimax Searches. ICCA Journal, Vol. 18, No. 2
Forum Posts
- Re: Quiescence search problems by David Blackman, rgcc, August 3, 1995 » Quiescence Search
References
- ↑ Don Beal (1995). An Integrated-Bounds-and-Values (IBV) Numeric Scale for Minimax Searches. ICCA Journal, Vol. 18, No. 2