# isomorphism -- computes an isomorphism between isomorphic posets

## Synopsis

• Usage:
pi' = isomorphism(P, Q)
• Inputs:
• P, an instance of the type Poset,
• Q, an instance of the type Poset,
• Outputs:
• pi', , which specifies a partial order preserving bijection from the ground set of $P$ to the ground set of $Q$

## Description

Two posets are isomorphic if there is a partial order preserving bijection between the ground sets of the posets which preserves the specified ground set partitions.

 i1 : isomorphism(divisorPoset (2*3*5), booleanLattice 3) o1 = HashTable{1 => 000 } 2 => 001 3 => 010 5 => 100 6 => 011 10 => 101 15 => 110 30 => 111 o1 : HashTable

This method was inspired by John Stembridge's Maple package available at http://www.math.lsa.umich.edu/~jrs/maple.html#posets.