A graph-based regularity test for deterministic context-free languages

Optimal Test Sets for Context-Free Languages

A test set for a formal language (set of strings) L is a subset T of L such that for any two string homomorphisms f and g defined on L, if the restrictions of f and g on T are identical functions, then f and g are identical on the entire L. Previously, it was shown that there are context-free grammars for which smallest test sets are cubic in the size of the grammar, which gives a lower bound o...

Tape Bounds for Some Subclasses of Deterministic Context-Free Languages

There are several interesting observations to be made concerning the tape complexity of context-free languages. An early result given by Lewis et al. (1965) is that every context-free language can be recognized by an off-line deterministic Turing machine of O((log n) 2) tape complexity. This is still the best result known. Sudborough (1975) shows that if all linear context-free languages can be...

Regular Description of Context-Free Graph Languages

A set of (labeled) graphs can be de ned by a regular tree language and one regular string language for each possible edge label, as follows. For each tree t from the regular tree language the graph gr(t) has the same nodes as t (with the same labels), and there is an edge with label from node x to node y if the string of labels of the nodes on the shortest path from x to y in t belongs to the r...

Strong Iterative Pairs and The Regularity of Context-Free Languages

Contribution to deterministic top-down analysis of context-free languages

In the present paper a generalization of ZX(A:)-grammars is given, the notion of the switching function for such grammars is introduced and the model of the Parsing Machine using the switch­ ing function is given. We introduce the necessary notions and notation, mainly according to D. E. Knuth: An alphabet X is a finite nonempty set of symbols, and X* denotes the set of all strings on the alpha...