**4.2 Applications to test and verification**

A close connection exists between the entropy metrics and usage modelling (Whittaker, 1994) for program verification. Most non-exhaustive testing requires a mix of tests taken during nominal conditions along with tests sampled according to potentially rare conditions. This consideration takes into account the number of test vectors and the path coverage for testing. Any characterization at this stage will provide useful inputs to generating a stochastic measure of reliability. This could incorporate stochastic usage models and a log-likelihood metric is often used to compare between two state space probabilities. Between an entropic measure and a usage model, we can cover the temporal and path dimensions of a program's execution and its programmatic complexity.
