Addendum to: Computing Failure Frequency via Mixed Products of Availabilities and Unavailabilities

In a recent paper I forgot to consider situations in which the (fault tree) structure function, when transformed to a multilinear polynomial (of usual algebra), or in which system unavailability, given as a polynomial of component availabilities and/or unavailabilities, contains a constant term. It is shown that constant terms need not be considered since they do not influence failure frequency. A new proof is given for the main result of my above paper.