Exam 6: Syntax

____ are symbols used to distinguish between parts of a rule.

The lexical structure of a programming language is the structure of its ____.

A recognizer is a program that accepts or rejects strings based on whether they have occurred before.

Most modern languages are in a completely fixed format.

A grammar for which two distinct parse trees are possible for the same string is considered to be ambiguous.

Derivation is the process that replaces left-hand sides by choices of right-hand sides appearing in prior rules.

A grammar is considered to be context-free if ____.

In extended Backus-Naur form,square brackets [ ] indicate optional parts of the syntax.

Shift-reduce parsers shift tokens onto a stack before reducing strings to nonterminals.

____ are phrase structures that are broken down into further phrase structures.

A conflict between syntax and semantics arises when languages require certain strings to be predefined identifiers rather than reserved words.

In a regular expression,repetition is indicated by ____.

____ have been given an initial meaning for all programs in the language but are capable of being redefined.

Regular expressions can be used to describe tokens.

A context-free grammar consists of a series of ____.

The start symbol is used to identify the start of the grammar.

Backus-Naur forms are used to describe the syntax of programming languages such as Algol60.

A language is considered to be ____ when format has no effect on the program structure (other than to satisfy the principle of longest substring).

A ____ is the standard graphical depiction of syntax-directed semantics.

A ____ rule must be stated to overcome ambiguous grammars.