“…Although the probability of multiple simultaneous failures seems very difficult to compute, our first result below, motivated by Korshunov and Wang ( 2020 )[Thm 1.1], shows that ψ k ( S , T , u ) can be bounded by the multivariate Gaussian survival probability, namely by where When we can approximate p T ( u ) utilising Laplace asymptotic method, see e.g., Korshunov et al ( 2015 ), whereas for small and moderate values of u it can be calculated or simulated with sufficient accuracy. Our next result gives bounds for ψ k ( S , T , u ) in terms of p T ( u ).…”