6,235 research outputs found
State-of-the-art on evolution and reactivity
This report starts by, in Chapter 1, outlining aspects of querying and updating resources on
the Web and on the Semantic Web, including the development of query and update languages
to be carried out within the Rewerse project.
From this outline, it becomes clear that several existing research areas and topics are of
interest for this work in Rewerse. In the remainder of this report we further present state of
the art surveys in a selection of such areas and topics. More precisely: in Chapter 2 we give
an overview of logics for reasoning about state change and updates; Chapter 3 is devoted to briefly describing existing update languages for the Web, and also for updating logic programs;
in Chapter 4 event-condition-action rules, both in the context of active database systems and
in the context of semistructured data, are surveyed; in Chapter 5 we give an overview of some relevant rule-based agents frameworks
Deciding regular grammar logics with converse through first-order logic
We provide a simple translation of the satisfiability problem for regular
grammar logics with converse into GF2, which is the intersection of the guarded
fragment and the 2-variable fragment of first-order logic. This translation is
theoretically interesting because it translates modal logics with certain frame
conditions into first-order logic, without explicitly expressing the frame
conditions.
A consequence of the translation is that the general satisfiability problem
for regular grammar logics with converse is in EXPTIME. This extends a previous
result of the first author for grammar logics without converse. Using the same
method, we show how some other modal logics can be naturally translated into
GF2, including nominal tense logics and intuitionistic logic.
In our view, the results in this paper show that the natural first-order
fragment corresponding to regular grammar logics is simply GF2 without extra
machinery such as fixed point-operators.Comment: 34 page
A Survey of Languages for Specifying Dynamics: A Knowledge Engineering Perspective
A number of formal specification languages for knowledge-based systems has been developed. Characteristics for knowledge-based systems are a complex knowledge base and an inference engine which uses this knowledge to solve a given problem. Specification languages for knowledge-based systems have to cover both aspects. They have to provide the means to specify a complex and large amount of knowledge and they have to provide the means to specify the dynamic reasoning behavior of a knowledge-based system. We focus on the second aspect. For this purpose, we survey existing approaches for specifying dynamic behavior in related areas of research. In fact, we have taken approaches for the specification of information systems (Language for Conceptual Modeling and TROLL), approaches for the specification of database updates and logic programming (Transaction Logic and Dynamic Database Logic) and the generic specification framework of abstract state machine
Belief Semantics of Authorization Logic
Authorization logics have been used in the theory of computer security to
reason about access control decisions. In this work, a formal belief semantics
for authorization logics is given. The belief semantics is proved to subsume a
standard Kripke semantics. The belief semantics yields a direct representation
of principals' beliefs, without resorting to the technical machinery used in
Kripke semantics. A proof system is given for the logic; that system is proved
sound with respect to the belief and Kripke semantics. The soundness proof for
the belief semantics, and for a variant of the Kripke semantics, is mechanized
in Coq
A History of Until
Until is a notoriously difficult temporal operator as it is both existential
and universal at the same time: A until B holds at the current time instant w
iff either B holds at w or there exists a time instant w' in the future at
which B holds and such that A holds in all the time instants between the
current one and w'. This "ambivalent" nature poses a significant challenge when
attempting to give deduction rules for until. In this paper, in contrast, we
make explicit this duality of until to provide well-behaved natural deduction
rules for linear-time logics by introducing a new temporal operator that allows
us to formalize the "history" of until, i.e., the "internal" universal
quantification over the time instants between the current one and w'. This
approach provides the basis for formalizing deduction systems for temporal
logics endowed with the until operator. For concreteness, we give here a
labeled natural deduction system for a linear-time logic endowed with the new
operator and show that, via a proper translation, such a system is also sound
and complete with respect to the linear temporal logic LTL with until.Comment: 24 pages, full version of paper at Methods for Modalities 2009
(M4M-6
- …