Test Sequence Generation for the U-method
Step 1. find a spanning tree from the initial state to every states.
Step 2.(a-part)
For each state j do
generate a sequence from the initial state to state j.
generate the UIO sequence for state j.
generate a sequence to return to the initial state.
Step 3.(b-part)
For each transition (j,k;i/o) do
generate [i/o]
generate a UIO sequence for state k
generate a sequence to return to the initial state