Which of the following grammar rules violate the requirements of an operator grammar? P, Q, R are nonterminals, and r, s, t are terminals.

$$\eqalign{ & 1.\,P \to QR \cr & 2.\,P \to QsR \cr & 3.\,P \to \varepsilon \cr & 4.\,P \to QtRr \cr} $$

Consider the grammar with the following translation rules and E as the start symbol.

$$\eqalign{ & E \to {E_1}\# T\,\,\left\{ {E.value = {E_1}.value*T.value} \right\} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,|T\,\,\,\,\,\,\,\,\,\,\,\,\left\{ {E.value = T.value} \right\} \cr & T \to {T_1}\& F\,\,\,\left\{ {T.value = {T_1}.value*F.value} \right\} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,F\,\,\,\,\,\,\,\,\,\,\,\left\{ {T.value = F.value} \right\} \cr & F \to num\,\,\,\,\,\,\,\left\{ {F.value = num.value} \right\} \cr} $$

Compute E.value for the root of the parse tree for the expression:
2 # 3 & 5 # 6 & 4.

Consider the grammar shown below.

$$\eqalign{ & S \to CC \cr & C \to cC\,|\,d \cr} $$

This grammar is

Consider the translation scheme shown below

$$\eqalign{ & S \to TR \cr & R \to + T\left\{ {pr{\mathop{\rm int}} (' + ');} \right\}\,R\,|\,\varepsilon \cr & T \to num\,\left\{ {pr{\mathop{\rm int}} (num.val);} \right\} \cr} $$

Here num is a token that represents an integer and num.val represents the corresponding integer value. For an input string '9 + 5 + 2', this translation scheme will print