A Sufficient and Necessary Condition for the Absolute Consistency of XML DTDs

Consistency of DTDs (or Schema) is a rising topic in XML research. In this paper, a sufficient and necessary condition for consistency of XML DTDs and an algorithm with high efficiency for DTDs consistency checking, of which worst time complexity is O(n), are proposed. Moreover, considering that a consistent DTD may have inconsistent sub-structures, notion of absolute consistency of DTDs is formalized. A sufficient and necessary condition for absolute consistency of XML DTDs and an algorithm for checking the absolute consistency of DTDs, of which time complexity is 0(n), are also offered.