A restricted type of context-free grammar, namely one in which all productions have the form
i.e. each right-hand side consists of a terminal followed by (zero or more) nonterminals. Any context-free language is generated by such a grammar, except that derivation of the empty string, Λ, requires the additional production
One significance of this form is that it makes clear the existence of an equivalent pushdown automaton: on reading
b the PDA can pop
A from the stack and push
C1…
Cn.