ZobristDistribution< D > Class Template Reference

HDA*[Z]: Zobrist hashing of the features of the state. More...

#include <PBeFS/astar/Distribution.h>

Public Member Functions
	ZobristDistribution (const D &domain, std::uint64_t seed=1)
	constructor, drawing the table of D from the seed
std::uint64_t	hash (const state_t< D > &s) const
	the Zobrist hash of s
std::uint32_t	key (const state_t< D > &s) const
	the key of s, the high 32 bits of its hash
unsigned	owner (const state_t< D > &s, unsigned p) const
	the owner of s among p workers, that of its key
std::uint32_t	key (std::uint32_t k, const state_t< D > &s, const state_t< D > &t) const
	the key of t, a successor of s whose key is k

Static Public Member Functions
static std::string	name (void)
	the name in the notation of Jinnai and Fukunaga

Detailed Description

template<FeatureDomain D>
class PBeFS_di_unipi_it::ZobristDistribution< D >

HDA*[Z]: Zobrist hashing of the features of the state.

\( Z( s ) = R[ x_0 ] \oplus \cdots \oplus R[ x_n ] \), where \( x_0 , \ldots , x_n \) are the features of \( s \), \( R \) a table of random 64-bit strings and \( \oplus \) the exclusive or of the bits [see Zobrist, 1970, and Kishimoto, Fukunaga and Botea, AIJ 2013]. Zobrist hashing is simple tabulation hashing, which is 3-independent: it spreads the states uniformly over the workers, but nearly every successor lands on another worker than its parent.

Constructor & Destructor Documentation

ZobristDistribution()

template<FeatureDomain D>

ZobristDistribution ( const D & domain, std::uint64_t seed = 1 )

inlineexplicit

constructor, drawing the table of D from the seed

Member Function Documentation

hash()

template<FeatureDomain D>

std::uint64_t hash ( const state_t< D > & s ) const

inlinenodiscard

the Zobrist hash of s

key() [1/2]

template<FeatureDomain D>

std::uint32_t key ( const state_t< D > & s ) const

inlinenodiscard

the key of s, the high 32 bits of its hash

key() [2/2]

template<FeatureDomain D>

std::uint32_t key ( std::uint32_t k, const state_t< D > & s, const state_t< D > & t ) const

inlinenodiscard

the key of t, a successor of s whose key is k

Equal to key( t ), but it reads the entries of the features that the move changes only [see IncrementalFeatureDomain].

name()

template<FeatureDomain D>

std::string name ( void )

inlinestaticnodiscard

the name in the notation of Jinnai and Fukunaga

owner()

template<FeatureDomain D>

unsigned owner ( const state_t< D > & s, unsigned p ) const

inlinenodiscard

the owner of s among p workers, that of its key

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The documentation for this class was generated from the following file:

• PBeFS/astar/Distribution.h