#### 5.5 Characterization Set

Most methods for generating tests from FSMs make use of an important set known as the *characterization set. *This set is usually denoted by *W *and is sometimes referred to as the *W**-*set*. *In this section, we explain how one can derive a *W-*set, given the description of an FSM. Let us examine the definition of the *W-*set.

The characterization set W for a minimal FSM Μ is a finite set of strings over the input alphabet of Μ such that for each pair of states (*r*, *s*) in Μ there exists at least one string in W that distinguishes state *r *from state *s.*

Let *Μ = *(*X*,* Y*,* Q*,* q*_{1}, *δ*, *O*) be an FSM that is minimal and complete. A characterization set for M, denoted as *W*, is a finite set of input sequences that distinguish the behavior of ...

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