# Peter Naur

> 1928–2016 · Computer Scientist
>
> **Recorded contribution:** ALGOL 60; Backus-Naur Form; coined "datalogy"

## How to use this dossier

Read for a causal chain, not a hero story: inherited problem → contribution → mechanism → downstream capability → limit. Then close the page and complete the reconstruction exercise from memory.

## 1. Historical orientation

Peter Naur (1928–2016) was a Danish computer scientist, astronomer, and editor whose work helped make programming-language description precise. He edited the influential ALGOL 60 report and refined the grammar notation introduced by John Backus; 'Backus–Naur Form' recognizes both contributions, though Naur himself preferred Backus Normal Form. He also argued that programming is 'theory building': the vital product is not only text and documentation but the development team's working understanding of the problem and design. Naur coined the Danish term datalogy for a human-centered study of data processes and resisted overly mechanical accounts of software creation.

## 2. The problem inherited

International language designers needed an unambiguous, implementation-independent way to specify ALGOL syntax, while software practice often treated programs as documents detached from developers' understanding.

## 3. The central contribution

Naur organized ALGOL 60's language report and formal productions into a readable standard, then articulated a theory-centered view of programming knowledge and maintenance.

## 4. Reconstruct the mechanism

1. Name each syntactic category, such as expression or statement, with a nonterminal symbol.
2. Define alternatives as productions composed from terminal tokens and other nonterminals.
3. Recursively expand a start category to determine which token sequences are syntactically legal.
4. Use the shared grammar to guide parser construction, test examples, and resolve disagreements independently of one compiler.

## 5. What changed downstream

- ALGOL 60 strongly influenced later block-structured languages and algorithm publication.
- BNF became standard notation in language specifications, textbooks, and compiler tools.
- Theory building anticipated modern concerns about tacit architectural knowledge and maintainability.

## 6. Attribution, limits, and uncertainty

- Backus introduced the underlying notation, and ALGOL 60 was an international committee achievement edited by Naur.
- Grammar specifies surface structure, while semantic meaning and implementation behavior require additional definitions.
- The theory-building essay is an interpretive account of software work, not a predictive formal theory validated for every team.

## 7. Reconstruction lab

Write BNF for arithmetic with precedence and conditionals, generate three valid and three invalid strings, and hand-build parse trees. Give the grammar to another learner without prose and record which semantic questions it cannot answer.

## 8. Evidence trail

- [Revised Report on the Algorithmic Language ALGOL 60](https://doi.org/10.1145/366193.366201) — Communications of the ACM
- [Programming as Theory Building](https://pages.cs.wisc.edu/~remzi/Naur.pdf) — Peter Naur Archive

---

*Research checked 2026-08-09. Dates, roles, and claims about living people are historical snapshots. Linked sources remain the authority; this dossier is original instructional synthesis.*