openInterval -- computes the subposet contained strictly between two points

• Usage:

  I = openInterval(P, a, b)

• Inputs:
  • P, an instance of the type Poset,
  • a, a thing, an element of the poset
  • b, a thing, an element of the poset
• Outputs:
  • I, an instance of the type Poset, the open interval in $P$ between $a$ and $b$

i1 : P = booleanLattice 3;

i2 : openInterval(P, "001", "111")

o2 = Relation Matrix: | 1 0 |
                      | 0 1 |

o2 : Poset