 The form of a proposition s with respect to a sequence i of ideas or (as an abbreviation) the i-form of s is the set of all \(i\)-variants of \(s\), provided that at least one of the \(i_k\)s is contained in \(s\). (For cases in which this proviso is not met, neither an \(i\)-variant of \(s\) nor the \(i\)-form of \(s\) is defined.)