No abstract

Attribute Krammars are an extension of contextfree grammars devised by Knuth as a mechanism for including the semantics of a context-free language with the syntax of the language. The circularity problem for a grammar is to determine whether the semantics for all possible sentences (programs) in fact will be well defined. It is proved that this problem is, in general, eomputationally intractable. Specifically, it is shown that any deterministic algorithm which solves the problem must for infinitely many eases use an exponential amount of time. An improved version of Knuth's cireularity testing algorithm is also given, which actually solves the prohlem within exponential time.

No abstract

No abstract

No abstract