0. Executional abstraction -- 1. The role of programming languages -- 2. States and their characterization -- 3. The characterization of semantics -- 4. The semantic characterization of a programming language -- 5. Two theorems -- 6. On the design of properly terminating constructs -- 7. Euclid's algorithm revisited -- 8. The formal treatment of some small examples -- 9. On nondeterminacy being bounded -- 10. An essay on the notion: "the scope of variables" -- 11. Array variables -- 12. The linear search algorithm -- 13. The problem of the next permutation -- 14. The problem of the Dutch national flag -- 15. Updating a sequential file -- 16. Merging problems revisited -- 17. An exercise attributed to R.W. Hamming -- 18. The pattern matching problem -- 19. Writing a number as the sum of two squares -- 20. The problem of the smallest prime factor of a large number -- 21. The problem of the most isolated villages -- 22. The problem of the shortest subspanning tree -- 23. Rem's algorithm for the recording of equivalence classes -- 24. The problem of the convex hull in three dimensions -- 25. Finding the maximal strong components in a directed graph -- 26. On manuals and implementations -- 27. In retrospect.