1 research outputs found
The Possibility Problem for Probabilistic XML (Extended Version)
We consider the possibility problem of determining if a document is a
possible world of a probabilistic document, in the setting of probabilistic
XML. This basic question is a special case of query answering or tree automata
evaluation, but it has specific practical uses, such as checking whether an
user-provided probabilistic document outcome is possible or sufficiently
likely. In this paper, we study the complexity of the possibility problem for
probabilistic XML models of varying expressiveness. We show that the decision
problem is often tractable in the absence of long-distance dependencies, but
that its computation variant is intractable on unordered documents. We also
introduce an explicit matches variant to generalize practical situations where
node labels are unambiguous; this ensures tractability of the possibility
problem, even under long-distance dependencies, provided event conjunctions are
disallowed. Our results entirely classify the tractability boundary over all
considered problem variants.Comment: 20 pages, 1 table, 2 figures. This is the complete version (including
proofs) of work initially submitted as an extended abstract (without proofs)
at the AMW 2014 workshop and subsequently submitted (with proofs) at the BDA
2014 conference (no formal proceedings). This version integrates the feedback
from both rounds of review