Syntax Definition For Language Prototyping Stellingen

1. The parsing problem for context-free grammars with reject productions (without rejects in cycles) is decidable.

   Chapter 3 of this thesis

2. Scannerless parsing has not been introduced earlier because of the limitations of deterministic parsing techniques, in particular with respect to the expression of lexical disambiguation, not because of the alleged inefficiency of scannerless parsers.

3. For every type system there exists a data type that cannot be completely expressed in it without allowing junk.

4. De formalisering van de wiskunde wordt uitgevoerd door informatici.

   Jan Bergstra in masterclass Programmeren met Datatypen, Universiteit van Amsterdam, Oktober 1995

5. Formalismen met onbeslisbare eigenschappen worden ten onrechte negatief beoordeeld, zoals blijkt uit: (a) Het halting probleem is onbeslisbaar, maar er bestaan terminerende programma's. (b) De ambiguiteit van context-vrije grammatica's is onbeslisbaar, maar er bestaan niet-ambigue grammatica's. (c) Het ontleedprobleem voor twee-niveau grammatica's is onbeslisbaar, maar er bestaan twee-niveau grammatica's met terminerende ontleders.

6. The emphasis on the expression of (static) semantic properties of Algol68 has obscured the utility of two-level grammars for polymorphic syntax definition.

7. The parsing problem for finite-chain two-level grammars is decidable.

   Chapter 15 of this thesis

8. Programming leads to legacy systems.

9. Any method (such as parameterization) that relies on a-priori indication of the parts of programs or modules that can be adapted (instantiation) anticipates future applications and thereby restricts possibilities for reuse.

10. Semantic equivalence under some semantics does not necessarily have to entail equality in an algebra. For example, two functions can have the same result, but achieve it in a different way.

11. Conditional term rewriting is a good example of a paradigm that can function well for a long time despite its anomalies.

    See Kuhn --- The Structure of Scientific Revolutions

12. Het gebruik van `hoi' bij het afscheid komt voort uit het besef dat ieder einde ook een begin is.