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Macaulay2 web site
Posets
::
principalOrderIdeal
principalOrderIdeal -- computes the elements below a given element in a poset
Synopsis
Usage:
I = principalOrderIdeal(P, a)
Inputs:
P
,
an object of class
Poset
a
,
a
thing
, an element of the poset
Outputs:
I
,
a
list
, containing all elements less than or equal to the given elements
Description
The order ideal of a element of a poset is all the elements in the poset which are less than or equal to the given element.
i1 : P = booleanLattice 3;
i2 : principalOrderIdeal(P, "101") o2 = {000, 001, 100, 101} o2 : List
See also
filter
-- computes the elements above given elements in a poset
orderIdeal
-- computes the elements below given elements in a poset
principalFilter
-- computes the elements above a given element in a poset
Ways to use
principalOrderIdeal
:
principalOrderIdeal(Poset,Thing)