  Artificial Chemistries (ACs) are symbolic chemical metaphors for the
exploration of Artificial Life, with specific focus on the origin of life. In
this work we define a P system based artificial graph chemistry to understand
the principles leading to the evolution of life-like structures in an AC set up
and to develop a unified framework to characterize and classify symbolic
artificial chemistries by devising appropriate formalism to capture semantic
and organizational information. An extension of P system is considered by
associating probabilities with the rules providing the topological framework
for the evolution of a labeled undirected graph based molecular reaction
semantics.
