posetJoin -- determines the join for two elements of a poset

Synopsis

• Usage:
j = posetJoin(P, a, b)
• Inputs:
• P, an instance of the type Poset,
• a, , an element of the poset
• b, , an element of the poset
• Outputs:
• j, , the least element greater than both $a$ and $b$, if it exists

Description

The join of $a$ and $b$ in $P$, if it exists, is the unique least element greater than both $a$ and $b$.

 i1 : B = booleanLattice 3; i2 : posetJoin(B, "001", "100") o2 = {101} o2 : List