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flagPoset -- computes the subposet of specified ranks of a ranked poset

Synopsis

Description

The flag poset with respect to a list of rank indices is the subposet induced by the specified ranks. The maximal chains of the flag poset can be computed with the flagChains method.

i1 : P = booleanLattice 4;
 
i2 : rankFunction P

o2 = {0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4}

o2 : List
 
i3 : flagPoset(P, {2,3})

o3 = Relation Matrix: | 1 0 0 1 0 0 1 0 0 0 |
                      | 0 1 0 1 0 0 0 0 1 0 |
                      | 0 0 1 1 0 0 0 0 0 1 |
                      | 0 0 0 1 0 0 0 0 0 0 |
                      | 0 0 0 0 1 0 1 0 1 0 |
                      | 0 0 0 0 0 1 1 0 0 1 |
                      | 0 0 0 0 0 0 1 0 0 0 |
                      | 0 0 0 0 0 0 0 1 1 1 |
                      | 0 0 0 0 0 0 0 0 1 0 |
                      | 0 0 0 0 0 0 0 0 0 1 |

o3 : Poset
 
i4 : flagPoset(P, {1})

o4 = Relation Matrix: | 1 0 0 0 |
                      | 0 1 0 0 |
                      | 0 0 1 0 |
                      | 0 0 0 1 |

o4 : Poset

See also

Ways to use flagPoset :

For the programmer

The object flagPoset is a method function.