Chapter 3 | Describing Syntax and Semantics

True or False:

Syntax defines the meaning of programming language constructs.

False

True or False:

Semantics defines the meaning of statements in a programming language.

True

True or False:

Lexical analysis groups characters into tokens.

True

True or False:

A context-free grammar (CFG) is commonly used to describe semantics.

False

True or False:

BNF stands for Backus–Naur Form.

True

True or False:

In BNF, nonterminal symbols are typically written in angle brackets < >.

True

True or False:

Terminals in a grammar are symbols that can be further expanded.

False

True or False:

Ambiguity occurs when a grammar produces more than one parse tree for a single string.

True

True or False:

EBNF (Extended BNF) allows repetition and optional parts in grammar rules.

True

True or False:

Parse trees represent the semantic meaning of a program.

False

True or False:

A leftmost derivation always replaces the rightmost nonterminal first.

False

True or False:

Recursive descent parsers may require backtracking.

True

True or False:

Attribute grammars extend context-free grammars with attributes and rules.

True

True or False:

In attribute grammars, synthesized attributes pass information upward in the parse tree.

True

True or False:

Inherited attributes flow only upward in the parse tree.

False

True or False:

Static semantics involves properties checked at compile time.

True

True or False:

Type checking is a form of static semantics.

True

True or False:

Dynamic semantics refers to meaning that can be checked without execution.

False

True or False:

Operational semantics describes meaning by changes in an abstract machine’s state.

True

True or False:

Denotational semantics describes meaning using mathematical functions.

True

True or False:

Axiomatic semantics is based on predicate logic.

True

True or False:

Hoare triples are part of denotational semantics.

False

True or False:

A Hoare triple has the form {precondition} program {postcondition}.

True

True or False:

Operational semantics is the most abstract approach to describing semantics.

False

True or False:

Denotational semantics maps programming constructs to precise mathematical objects.

True

True or False:

Axiomatic semantics is mainly concerned with implementation efficiency.

False

True or False:

Regular expressions are sufficient to describe all programming language syntax.

False

True or False:

Context-free grammars can describe nested constructs such as balanced parentheses.

True

True or False:

All BNF grammars are guaranteed to be unambiguous.

False

True or False:

Arithmetic precedence rules can be expressed using context-free grammars.

True

True or False:

Static semantics cannot be described using grammar alone.

True

True or False:

Syntax-directed definitions link grammar rules with semantic actions.

True

True or False:

Attribute grammars cannot be used for static semantics checks.

False

True or False:

Denotational semantics is generally less mathematically precise than operational semantics.

False

True or False:

Axiomatic semantics uses logic to prove program correctness.

True

True or False:

Parse trees and derivations are used to represent semantics.

False

True or False:

BNF and EBNF are primarily concerned with describing syntax.

True

True or False:

Attribute grammars combine both syntax and semantics in a unified framework.

True

True or False:

In programming languages, syntax and semantics are unrelated.

False

True or False:

The study of semantics helps in understanding program correctness and reasoning.

True

The part of a programming language that defines the meaning of statements and constructs.

Semantics

The set of rules that defines the structure of programs and how symbols can be combined.

Syntax

The process of grouping characters from source code into meaningful tokens.

Lexical analysis

A formalism used to describe programming language syntax, not semantics.

Context-free grammar (CFG)

A notation for describing context-free grammars, commonly using angle brackets for nonterminals.

BNF (Backus–Naur Form)

Symbols in a grammar that cannot be expanded further.

Terminals

Occurs when a grammar can produce more than one parse tree for the same string.

Ambiguity

An extension of BNF that allows optional and repeated elements in grammar rules.

EBNF

Trees that represent the syntactic structure of a program.

Parse trees

A parsing strategy that may require backtracking when encountering multiple possible expansions.

Recursive descent parser

Grammars that are extended with attributes and rules to link syntax and semantics.

Attribute grammars

Attributes that pass information upward in the parse tree.

Synthesized attributes

Attributes that flow downward or across siblings in a parse tree.

Inherited attributes

Properties of a program that can be checked at compile time.

Static semantics

The process of verifying type correctness and other compile-time rules.

Type checking

Describes program meaning during execution rather than at compile time.

Dynamic semantics

Describes the meaning of a program by modeling state changes in an abstract machine.

Operational semantics

Describes programming constructs using precise mathematical functions.

Denotational semantics

Uses predicate logic to reason about program correctness.

Axiomatic semantics

A logical assertion of the form {precondition} program {postcondition}.

Hoare triple

The approach to describing semantics that focuses on proving program correctness rather than execution.

Axiomatic semantics

The formal system that maps programming constructs to precise mathematical objects.

Denotational semantics

Grammars capable of describing nested structures like balanced parentheses.

Context-free grammars (CFGs)

Grammars that may produce multiple parse trees for the same string are called…

Ambiguous grammars

The rules that define arithmetic precedence in programming languages can be expressed using this.

Context-free grammars

Describes properties of programs that cannot be enforced by grammar alone.

Static semantics

A method that links grammar rules directly with semantic actions.

Syntax-directed definitions

Grammars that can be used to check static semantics, like type consistency.

Attribute grammars

The formal approach to semantics that is less abstract and often models execution on an abstract machine.

Operational semantics

Trees or derivations that represent syntactic structure rather than semantic meaning.

Parse trees

A notation primarily concerned with describing syntax, such as grammar rules.

BNF or EBNF

A formalism that combines both syntax and semantics in a unified framework.

Attribute grammars

The study of meaning in programming languages, which helps reason about program correctness.

Semantics

Properties or rules of a program that can be enforced at compile-time rather than runtime.

Static semantics

The semantic approach that uses logic to prove correctness of programs.

Axiomatic semantics

Semantic method that describes meaning by mapping constructs to mathematical functions.

Denotational semantics

Semantic method that describes meaning via state changes in an abstract machine.

Operational semantics

A Hoare triple expresses correctness with a precondition, program, and postcondition.

{precondition} program {postcondition}

Dynamic semantics refers to meaning that is determined during program execution rather than at compile time.

Dynamic semantics