Notes on Structured Programming (EWD249)

Markdown transcription of Edsger W. Dijkstra's Notes on Structured Programming (EWD249, August 1969; second edition April 1970), one file per page of the source PDF.

• Source PDF: https://pure.tue.nl/ws/files/2408738/252825.pdf (89 pages)
• Transcription: pages/001.md … pages/089.md, one file per PDF page.
• File number = PDF page order. Pages 001–003 are the TU/e publication cover and front matter; the typescript itself begins at pages/003.md.
• Printed page numbers appear in each file as the typescript's running header (EWD249 - N). The printed number is 5 lower than the file number (file 040.md → EWD249 - 35).

Contents

Section	Printed page	File
Table of contents	—	004
To my reader.	0	005
On our inability to do much.	1	006
On the reliability of mechanisms.	4	009
On our mental aids.	8	013
On enumeration.	8	013
On mathematical induction.	9	014
On abstraction.	13	018
An example of a correctness proof.	15	020
On the validity of proofs versus the validity of implementations.	19	024
On understanding programs.	21	026
On comparing programs.	30	035
A first example of step-wise program composition.	35	040
On program families.	50	055
On trading storage space for computation speed.	53	058
On a program model.	57	062
A second example of step-wise program composition.	64	069
On what we have achieved.	75	080
On grouping and sequencing.	80	085

Notes on the transcription

• Text is transcribed faithfully from the page images; the author's original spelling, punctuation and typos are preserved rather than modernized.
• Typewritten programs, algorithms and mathematical displays are kept in fenced code blocks with their original indentation.
• Words underlined in the original running text are rendered as bold. Underlines inside fenced code blocks are not representable in Markdown and are therefore preserved only as plain text.
• Diagrams that cannot be reproduced as text are rendered as ASCII where simple, or described briefly.