Authors:
Gopalakrishnan Krishnasamy Sivaprakasam
1
and
Giora Slutzki
2
Affiliations:
1
Central State University, United States
;
2
Iowa State University, United States
Keyword(s):
Secrecy Preserving Reasoning, Knowledge Bases, Modalized Description Logic, Query Answering.
Related
Ontology
Subjects/Areas/Topics:
Agents
;
Artificial Intelligence
;
Collaboration and e-Services
;
e-Business
;
Enterprise Information Systems
;
Knowledge Engineering and Ontology Development
;
Knowledge Representation and Reasoning
;
Knowledge-Based Systems
;
Privacy, Safety and Security
;
Semantic Web
;
Soft Computing
;
Symbolic Systems
Abstract:
In this paper we study Secrecy-Preserving Query Answering problem under the Open World Assumption
(OWA) for ELH Knowledge Bases. Here ELH is a top-free description logic ELH augmented with a
modal operator ^. We employ a tableau procedure designed to compute a rooted labeled tree T which contains
information about some assertional consequences of the given knowledge base. Given a secrecy set S, which
is a finite set of assertions, we compute a function E, called an envelope of S, which assigns a set of assertions
to each node of T. E provides logical protection to the secrecy set S against the reasoning of a querying
agent. Once the tree T and an envelope E are computed, we define the secrecy-preserving tree TE. Based on
the information available in TE, assertional queries with modal operator ^ can be answered efficiently while
preserving secrecy. To the best of our knowledge, this work is first one studying secrecy-preserving reasoning
in description logic augmented with modal opera
tor ^. When the querying agent asks a query q, the reasoner
answers “Yes” if information about q is available in TE; otherwise, the reasoner answers “Unknown”. Being
able to answer “Unknown” plays a key role in protecting secrecy under OWA. Since we are not computing
all the consequences of the knowledge base, answers to the queries based on just secrecy-preserving tree TE
could be erroneous. To fix this problem, we further augment our algorithms by providing recursive query
decomposition algorithm to make the query answering procedure foolproof.
(More)