Abstract of Paper

XML Grammars
by Jean Berstel, Luc Boasson


XML documents are described by a document type definition (DTD). An
XML­grammar is a formal grammar that captures the syntactic features of a
DTD. We investigate properties of this family of grammars. We show that an
XML­language basically has a unique XML­grammar. We give two
characterizations of languages generated by XML­grammars, one is
set­theoretic, the other is by a kind of saturation property. We investigate
decidability problems and prove that some properties that are undecidable
for general context­free languages become decidable for XML­languages.