  One should understand the difference between regular and singular limiting relations as follows. If the solutions of the relevant formulae or equations of the theory \(T_f\) are such that for small values of \(\varepsilon\) they smoothly approach the solutions of the corresponding formulas in \(T_c\), then Schema R will hold. For these cases we can say that the “limiting behavior” as \(\varepsilon \rightarrow 0\) equals the “behavior in the limit” where \(\varepsilon = 0\). On the other hand, if the behavior in the limit is of a fundamentally different character than the nearby solutions one obtains as \(\varepsilon \rightarrow 0\), then the schema will fail.