pushdown automata (pda)

Basic IdeaHere we want the sentential form to represent stackcontent.The grammar we construct uses variables of the form(q i Aq j ). We require the following relation betweengrammar and npda.(q i Aq j ) ∗ ⇒ v if and only if the npda erases A from thestack while reading v and going from q i to q j .Here “erasing” means bringing up the variable under Ain stack.Pushdown Automata – p. 15