2. Inductive problems ordinarily have fixed inputs, whereas deductive reasoning is often coincident with variable inputs. A function, the quintessential object in mathematical induction, has fixed inputs, but experts have little difficulty reasoning from available information. For example, size limitations may prohibit collection of an electron-ionization mass spectrum (EI-MS) of an unknown compound. A fixed input model that relies on EI-MS would be challenged by such a case, but a deductive approach would not rely on any single information source.