Tree isomorphism and smallest cycle base

[<wush1 AT gmx.de>]

Simple version:
Do you have methods concerning these problems?

Complex version:
I have this half grown idea of representing data as graph and then allowing
shifts in perspective trough certain transformations.
In each perspective the graph would be tested for patterns and similarities 
and
then based on a relationship graph given by the user
generate a new graph as output. Kind of a genetic programming with graphs.

For example: If I wanted to teach addition two input nodes (representing the
minimal perspective of two graphs) would be connected with directed edges to 
an
output node.
Then I present example data of inputs and output allowing the program to learn
the representation of numbers and kind of like with dna and amino acids use 
the
inputs as tempory components of the output structure.