# orderIdeal -- computes the elements below given elements in a poset

## Synopsis

• Usage:
I = orderIdeal(P, L)
• Inputs:
• P, an instance of the type Poset,
• L, a list, elements of the poset
• Outputs:
• I, a list, containing all elements less than or equal to at least one of the given elements

## Description

The order ideal of a given set of elements of a poset is all the elements in the poset which are less than or equal to at least one of the elements in the given set.

 i1 : P = booleanLattice 3; i2 : orderIdeal(P, {"001", "100"}) o2 = {000, 001, 100} o2 : List