Chapter 3, Problem 15PS

Explanation of Solution

Consider the following BNF:

<program> -> begin <stmt_list> end

<stmt_list> -> <stmt>

  | <stmt> ; <stmt_list>

<stmt> -> <var> = <expression>

<var>- A | B | C

<expression> - <var> + <var>

  |<var> - <var>

  |<var>

Conversion of the given BNF into the EBNF is as follow:

Enclosing an entity in curly braces indicates that it can be used indefinitely or left altogether as stated in section 3.3.2 of the book.

• So <stmt_list> can be defined as <stmt> or {<stmt>} use indefinitely after a <stmt>.
• Therefore, write the first two productions as:

<program> -> begin <stmt_list> end

<stmt_list> -> <stmt>{<stmt>}

• The next two productions are same as given since no EBNF rule applies to them...