13,186 research outputs found
On Properties of Update Sequences Based on Causal Rejection
We consider an approach to update nonmonotonic knowledge bases represented as
extended logic programs under answer set semantics. New information is
incorporated into the current knowledge base subject to a causal rejection
principle enforcing that, in case of conflicts, more recent rules are preferred
and older rules are overridden. Such a rejection principle is also exploited in
other approaches to update logic programs, e.g., in dynamic logic programming
by Alferes et al. We give a thorough analysis of properties of our approach, to
get a better understanding of the causal rejection principle. We review
postulates for update and revision operators from the area of theory change and
nonmonotonic reasoning, and some new properties are considered as well. We then
consider refinements of our semantics which incorporate a notion of minimality
of change. As well, we investigate the relationship to other approaches,
showing that our approach is semantically equivalent to inheritance programs by
Buccafurri et al. and that it coincides with certain classes of dynamic logic
programs, for which we provide characterizations in terms of graph conditions.
Therefore, most of our results about properties of causal rejection principle
apply to these approaches as well. Finally, we deal with computational
complexity of our approach, and outline how the update semantics and its
refinements can be implemented on top of existing logic programming engines.Comment: 59 pages, 2 figures, 3 tables, to be published in "Theory and
Practice of Logic Programming
A Brief History of Updates of Answer-Set Programs
Funding Information: The authors would like to thank JosĂ© Alferes, Martin Baláz, Federico Banti, Antonio Brogi, Martin Homola, LuĂs Moniz Pereira, Halina Przymusinska, Teodor C. Przymusinski, and Theresa Swift, with whom they worked on the topic of this paper over the years, as well as Ricardo Gonçalves and Matthias Knorr for valuable comments on an earlier draft of this paper. The authors would also like to thank the anonymous reviewers for their insightful comments and suggestions, which greatly helped us improve this paper. The authors were partially supported by Fundação para a CiĂŞncia e Tecnologia through projects FORGET (PTDC/CCI-INF/32219/2017) and RIVER (PTDC/CCI-COM/30952/2017), and strategic project NOVA LINCS (UIDB/04516/2020). Publisher Copyright: © The Author(s), 2022. Published by Cambridge University Press.Over the last couple of decades, there has been a considerable effort devoted to the problem of updating logic programs under the stable model semantics (a.k.a. answer-set programs) or, in other words, the problem of characterising the result of bringing up-to-date a logic program when the world it describes changes. Whereas the state-of-the-art approaches are guided by the same basic intuitions and aspirations as belief updates in the context of classical logic, they build upon fundamentally different principles and methods, which have prevented a unifying framework that could embrace both belief and rule updates. In this paper, we will overview some of the main approaches and results related to answer-set programming updates, while pointing out some of the main challenges that research in this topic has faced.publishersversionpublishe
Fundamental Limitations of Disturbance Attenuation in the Presence of Side Information
In this paper, we study fundamental limitations of disturbance attenuation of feedback systems, under the assumption that the controller has a finite horizon preview of the disturbance. In contrast with prior work, we extend Bode's integral equation for the case where the preview is made available to the controller via a general, finite capacity, communication system. Under asymptotic stationarity assumptions, our results show that the new fundamental limitation differs from Bode's only by a constant, which quantifies the information rate through the communication system. In the absence of asymptotic stationarity, we derive a universal lower bound which uses Shannon's entropy rate as a measure of performance. By means of a case-study, we show that our main bounds may be achieved
Computer-Aided Discovery and Categorisation of Personality Axioms
We propose a computer-algebraic, order-theoretic framework based on
intuitionistic logic for the computer-aided discovery of personality axioms
from personality-test data and their mathematical categorisation into formal
personality theories in the spirit of F.~Klein's Erlanger Programm for
geometrical theories. As a result, formal personality theories can be
automatically generated, diagrammatically visualised, and mathematically
characterised in terms of categories of invariant-preserving transformations in
the sense of Klein and category theory. Our personality theories and categories
are induced by implicational invariants that are ground instances of
intuitionistic implication, which we postulate as axioms. In our mindset, the
essence of personality, and thus mental health and illness, is its invariance.
The truth of these axioms is algorithmically extracted from histories of
partially-ordered, symbolic data of observed behaviour. The personality-test
data and the personality theories are related by a Galois-connection in our
framework. As data format, we adopt the format of the symbolic values generated
by the Szondi-test, a personality test based on L.~Szondi's unifying,
depth-psychological theory of fate analysis.Comment: related to arXiv:1403.200
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