This method is based on the idea of generating all derivative
states from a starting state (e.g. IDLE), and exhaustively
checking the legality of the sequences generated.
The word <#855#> perturbation<#855#>
is used to mean all state changes that are visible externally
from the protocol end point, like transmission of packets, or
reception of packet on a channel etc.
The validation method involves generating all legal trees of
state sequences, and therefore can result in infinite sized
output. Methods for limiting the expansion of the tree to
include interesting cases exist.
Loop detection is essential for finding stable sequence.