“…A number of formal verification techniques have been proposed for DNNs, including constraint-solving [8,16,19,22,24,32,39,47], abstract interpretation [21,37,59,60,84], layerby-layer exhaustive search [29], global optimisation [15,55,56], convex relaxation [31,49,50], functional approximation [76], reduction to two-player games [77,79], and star-set-based abstraction [66,67]. Sampling-based methods are adopted to probabilistic robustness verification in [2,3,12,45,74,75]. Most of them provide sound DNN robustness estimation in the form of a norm ball, but typically for very small networks or with pessimistic estimation of the norm ball radius.…”