A study on the extended unique input/output sequence

The unique input/output (UIO) sequence is an important state identification technique in the FSM-based protocol conformance testing. However, some states of a FSM might have no UIO sequence. To address the above problem, this paper introduces an extended UIO sequence, called a GUIO sequence, which distinguishes a designated state from the remaining states by a group-by-group means. The problem of searching the optimal GUIO sequence is NP-hard. In this paper, we present a GUIO search method based on a greedy heuristics and a φ-hop search approach. The proposed method can obtain desirable GUIO sequences with relatively low computational complexity.