Section: New Results
An Efficient Translation from a modal -Calculus with Converse to Tree Automata
In [16], we presented a direct translation from a sub-logic of -calculus to non-deterministic binary automata of finite trees. The logic is an alternation-free modal -calculus, restricted to finite trees and where formulae are cycle-free. This logic is expressive enough to encode significant fragments of query languages (such as Regular XPath). The size of the generated automaton (the number of transitions) is bounded by where is the size of a Fischer-Ladner closure of the formula. This is an improvement over previous translations in . We have implemented our translation. In practice, our prototype effectively decides static analysis problems that were beyond reach, such as the XPath containment problem with DTDs of significant size.