Backus–Naur Form

E129070

formal grammar notation metalanguage syntax specification language

Backus–Naur Form is a formal notation used to define the syntax of programming languages and other formal grammars in a precise, structured way.

Try in SPARQL Jump to: Surface forms Disambiguation Statements Elicitation Referenced by

All labels observed (6)

Label	Occurrences
Backus–Naur form	5
Backus–Naur Form canonical	4
BNF	2
Extended Backus–Naur Form	2
Backus Normal Form	1
backus–naur form	1

How this entity was disambiguated

This entity first appeared as the object of triple T1117740 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.

NED1 Entity disambiguation (via context triple) gpt-5-mini-2025-08-07

Target entity: Backus–Naur Form
Context triple: [ALGOL 60, hasSyntaxDescription, Backus–Naur Form]

A. Chomsky hierarchy
The Chomsky hierarchy is a classification of formal grammars into four types that correspond to increasing levels of generative power and computational complexity in formal language theory.
B. ALGOL 60
ALGOL 60 is an early high-level programming language that pioneered block structure and lexical scoping, profoundly influencing the design of many later languages.
C. General and Rational Grammar
General and Rational Grammar is a 17th-century French linguistic treatise from the Port-Royal school that seeks to explain the universal, rational principles underlying all human languages.
D. Algol 68S
Algol 68S is a simplified subset of the Algol 68 programming language designed to make the language easier to implement and use.
E. Algol 68
Algol 68 is a high-level, structured programming language from the ALGOL family, notable for its orthogonal design and influence on many later languages.
F. None of above. chosen
G. Unsure - the case is ambiguous/there is not enough information to decide.

NED2 Entity disambiguation (via description) gpt-5-mini-2025-08-07

Target entity: Backus–Naur Form
Target entity description: Backus–Naur Form is a formal notation used to define the syntax of programming languages and other formal grammars in a precise, structured way.

A. Chomsky hierarchy
The Chomsky hierarchy is a classification of formal grammars into four types that correspond to increasing levels of generative power and computational complexity in formal language theory.
B. ALGOL 60
ALGOL 60 is an early high-level programming language that pioneered block structure and lexical scoping, profoundly influencing the design of many later languages.
C. General and Rational Grammar
General and Rational Grammar is a 17th-century French linguistic treatise from the Port-Royal school that seeks to explain the universal, rational principles underlying all human languages.
D. Algol 68S
Algol 68S is a simplified subset of the Algol 68 programming language designed to make the language easier to implement and use.
E. Algol 68
Algol 68 is a high-level, structured programming language from the ALGOL family, notable for its orthogonal design and influence on many later languages.
F. None of above. chosen

Statements (44)

Predicate	Object
instanceOf	formal grammar notation ⓘ metalanguage ⓘ syntax specification language ⓘ
alsoKnownAs	Backus–Naur Form ⓘ surface form: BNF Backus–Naur Form ⓘ surface form: Backus Normal Form
basedOn	context-free grammar theory ⓘ
cannotExpress	context-sensitive language constraints ⓘ
category	formal methods ⓘ programming language syntax ⓘ
comparedWith	regular expressions ⓘ
definesRelationBetween	nonterminal symbols and sequences of terminals and nonterminals ⓘ
fieldOfUse	compiler construction ⓘ computer science ⓘ formal language theory ⓘ programming language theory ⓘ
firstUsedFor	ALGOL 60 ⓘ surface form: ALGOL 60 language specification
hasAbbreviation	Backus–Naur Form self-linksurface differs ⓘ surface form: BNF
hasComponent	metasymbols ⓘ nonterminal symbols ⓘ production rules ⓘ terminal symbols ⓘ
hasVariant	Augmented Backus–Naur Form ⓘ Backus–Naur Form self-linksurface differs ⓘ surface form: Extended Backus–Naur Form
influenced	Augmented Backus–Naur Form ⓘ Backus–Naur Form self-linksurface differs ⓘ surface form: Extended Backus–Naur Form many programming language specifications ⓘ syntax diagrams ⓘ
moreExpressiveThan	regular expressions for nested structures ⓘ
namedAfter	John Backus ⓘ Peter Naur ⓘ
property	can describe all context-free languages ⓘ
roleInSpecification	provides precise, unambiguous syntax definitions ⓘ
typicalMetasymbol	::= ⓘ < > ⓘ \| ⓘ
typicalNotationForNonterminals	angle brackets around names ⓘ
typicalNotationForTerminals	literal character sequences ⓘ
usedFor	defining context-free grammars ⓘ defining the syntax of programming languages ⓘ describing language syntax in language specifications ⓘ specifying formal languages ⓘ
usedIn	documentation of data formats ⓘ language reference manuals ⓘ standards documents for programming languages ⓘ

How these facts were elicited

Referenced by (15)

Full triples — surface form annotated when it differs from this entity's canonical label.

ALGOL 60 → hasSyntaxDescription → Backus–Naur Form ⓘ

ALGOL 60 → wasDescribedUsing → Backus–Naur Form ⓘ

IFIP Working Group 2.1 → relatedTo → Backus–Naur Form ⓘ

this entity surface form: backus–naur form

Backus–Naur Form → alsoKnownAs → Backus–Naur Form ⓘ

this entity surface form: BNF

Backus–Naur Form → alsoKnownAs → Backus–Naur Form ⓘ

this entity surface form: Backus Normal Form

Backus–Naur Form → influenced → Backus–Naur Form self-linksurface differs ⓘ

this entity surface form: Extended Backus–Naur Form

Backus–Naur Form → hasVariant → Backus–Naur Form self-linksurface differs ⓘ

this entity surface form: Extended Backus–Naur Form

Backus–Naur Form → hasAbbreviation → Backus–Naur Form self-linksurface differs ⓘ

this entity surface form: BNF

John Backus → notableWork → Backus–Naur Form ⓘ