rooted_tree_isomorphism

rooted_tree_isomorphism(t1, root1, t2, root2)

Given two rooted trees t1 and t2, with roots root1 and root2 respectively this routine will determine if they are isomorphic.

These trees may be either directed or undirected, but if they are directed, all edges should flow from the root.

It returns the isomorphism, a mapping of the nodes of t1 onto the nodes of t2, such that two trees are then identical.

Note that two trees may have more than one isomorphism, and this routine just returns one valid mapping.

Parameters:

`t1`NetworkX graph

One of the trees being compared

`root1`a node of t1 which is the root of the tree

`t2`undirected NetworkX graph

The other tree being compared

`root2`a node of t2 which is the root of the tree

This is a subroutine used to implement `tree_isomorphism`, but will

be somewhat faster if you already have rooted trees.

Returns:

isomorphismlist

A list of pairs in which the left element is a node in t1 and the right element is a node in t2. The pairs are in arbitrary order. If the nodes in one tree is mapped to the names in the other, then trees will be identical. Note that an isomorphism will not necessarily be unique.

If t1 and t2 are not isomorphic, then it returns the empty list.