Frequency of exceedance any peak exceeding is . Its complement, is the probability of exceedance, the probability that has been exceeded at least once by time . This probability can be useful to estimate whether an extreme event will occur during a specified time period, such as the lifespan of a structure or the duration of an operation. If is small, for example for the frequency of a rare event occurring in a short time period, then Under this assumption, the frequency of exceedance is equal to the probability of exceedance per unit time, , and the probability of exceedance can be computed
Shannon capacity of a graph "α"("G"). The effective number of signals transmitted per unit time step is the "k"th root of this number, "α"("G"). Using these concepts, the Shannon capacity may be defined as the limit (as "k" becomes arbitrarily large) of the effective number of signals per time step of arbitrarily long confusion-free codes. The computational complexity of the Shannon capacity is unknown, and even the value of the Shannon capacity for certain small graphs such as "C" (a cycle graph of seven vertices) remains unknown. A natural approach to this problem would be to compute a finite number of powers of the given