A non-terminal A is useless if there is no derivation from the start symbol to a string of tokens in which A appears.
(a) Give a mathematical formulation of this property.
(b) Is it likely that a programming language grammar will have a useless symbol? Explain
(c) Show that, if a grammar has a useless symbol, the computation of the First and Fellow sets as given in this chapter may produce sets that are too large to accurately construct an LL(1) parsing table.