org.thegalactic.lattice

Class LatticeFactory

java.lang.Object

org.thegalactic.lattice.LatticeFactory

public class LatticeFactory
extends Object

This class provides a few methods to constructs lattice examples.

Author:

jeff

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LatticeFactory() Empty constructor.

Method Summary

Modifier and Type	Method and Description
static Lattice	booleanAlgebra(int n) Returns the boolean algebra of cardinal 2^n.
static Lattice	doublingConvex(Lattice l, DAGraph c) Returns lattice l in which convex c has been doubled.
static Lattice	permutationLattice(int n) Returns the lattice of permutations of 1..n.
static Lattice	product(Lattice l, Lattice r) Returns the lattice cartesian product of l and r.
static Lattice<Integer,?>	random(int nb) Returns a randomly generated lattice with nb nodes.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LatticeFactory

protected LatticeFactory()

Empty constructor.

Method Detail

random

public static Lattice<Integer,?> random(int nb)

Returns a randomly generated lattice with nb nodes.

Parameters:

nb - Number of nodes in the randomly generated lattice

Returns:

a randomly generated lattice with nb nodes

booleanAlgebra

public static Lattice booleanAlgebra(int n)

Returns the boolean algebra of cardinal 2^n.

Parameters:

n - cardinal of the boolean algebra return by this method is 2^n

Returns:

the boolean algebra of cardinal 2^n

permutationLattice

public static Lattice permutationLattice(int n)

Returns the lattice of permutations of 1..n.

Permutation are ordered as follows : A permutation s2 is a succesor of a permutation s1, if s2 is obtained from s1 by inverting two consecutive elements i and j such that before inversion j > i.

Example : 124356 has following successors 214356, 142356, 124536 and 124365.

The bottom of this lattice is identity (for exemple 123456) and the top is for instance 654321.

Parameters:

n - the lattice of permutations of the set 1..n

Returns:

the lattice of permutations of 1..n.

product

public static Lattice product(Lattice l,
                              Lattice r)

Returns the lattice cartesian product of l and r.

A node in the product is a cartesian product of two nodes

There is an edge (n1, m1) -> (n2, m2) if and only if there are edges n1 -> n2 and m1 -> m2

Parameters:

l - Lattice of the left hand side of the product

r - Lattice of the right hand side of the product

Returns:

the lattice cartesian product of l and r

doublingConvex

public static Lattice doublingConvex(Lattice l,
                                     DAGraph c)

Returns lattice l in which convex c has been doubled.

Parameters:

l - a lattice

c - a convex subset of l, to be doubled.

Returns:

a lattice construct from l by doubling the convex subset c.