The Good and the Bad: Using Neuron Coverage as a DNN Validation Technique

Verification and validation (V&V) is a crucial step for the certification and deployment of deep neural networks (DNNs). Neuron coverage, inspired by code coverage in software testing, has been proposed as one such V&V method. We provide a summary of different neuron coverage variants and their inspiration from traditional software engineering V&V methods. Our first experiment shows that novelty and granularity are important considerations when assessing a coverage metric. Building on these observations, we provide an illustrative example for studying the advantages of pairwise coverage over simple neuron coverage. Finally, we show that there is an upper bound of realizable neuron coverage when test data are sampled from inside the operational design domain (in-ODD) instead of the entire input space.