135,957 research outputs found
Belief merging within fragments of propositional logic
Recently, belief change within the framework of fragments of propositional
logic has gained increasing attention. Previous works focused on belief
contraction and belief revision on the Horn fragment. However, the problem of
belief merging within fragments of propositional logic has been neglected so
far. This paper presents a general approach to define new merging operators
derived from existing ones such that the result of merging remains in the
fragment under consideration. Our approach is not limited to the case of Horn
fragment but applicable to any fragment of propositional logic characterized by
a closure property on the sets of models of its formulae. We study the logical
properties of the proposed operators in terms of satisfaction of merging
postulates, considering in particular distance-based merging operators for Horn
and Krom fragments.Comment: To appear in the Proceedings of the 15th International Workshop on
Non-Monotonic Reasoning (NMR 2014
An Enhanced Multiway Sorting Network Based on n-Sorters
Merging-based sorting networks are an important family of sorting networks.
Most merge sorting networks are based on 2-way or multi-way merging algorithms
using 2-sorters as basic building blocks. An alternative is to use n-sorters,
instead of 2-sorters, as the basic building blocks so as to greatly reduce the
number of sorters as well as the latency. Based on a modified Leighton's
columnsort algorithm, an n-way merging algorithm, referred to as SS-Mk, that
uses n-sorters as basic building blocks was proposed. In this work, we first
propose a new multiway merging algorithm with n-sorters as basic building
blocks that merges n sorted lists of m values each in 1 + ceil(m/2) stages (n
<= m). Based on our merging algorithm, we also propose a sorting algorithm,
which requires O(N log2 N) basic sorters to sort N inputs. While the asymptotic
complexity (in terms of the required number of sorters) of our sorting
algorithm is the same as the SS-Mk, for wide ranges of N, our algorithm
requires fewer sorters than the SS-Mk. Finally, we consider a binary sorting
network, where the basic sorter is implemented in threshold logic and scales
linearly with the number of inputs, and compare the complexity in terms of the
required number of gates. For wide ranges of N, our algorithm requires fewer
gates than the SS-Mk.Comment: 13 pages, 14 figure
Towards the implementation of a preference-and uncertain-aware solver using answer set programming
Logic programs with possibilistic ordered disjunction (or LPPODs) are a recently defined logic-programming framework based on logic programs with ordered disjunction and possibilistic logic. The framework inherits the properties of such formalisms and merging them, it supports a reasoning which is nonmonotonic, preference-and uncertain-aware. The LPPODs syntax allows to specify 1) preferences in a qualitative way, and 2) necessity values about the certainty of program clauses. As a result at semantic level, preferences and necessity values can be used to specify an order among program solutions. This class of program therefore fits well in the representation of decision problems where a best option has to be chosen taking into account both preferences and necessity measures about information. In this paper we study the computation and the complexity of the LPPODs semantics and we describe the algorithm for its implementation following on Answer Set Programming approach. We describe some decision scenarios where the solver can be used to choose the best solutions by checking whether an outcome is possibilistically preferred over another considering preferences and uncertainty at the same time.Postprint (published version
Magnetic skyrmion logic gates: conversion, duplication and merging of skyrmions
Magnetic skyrmions, which are topological particle-like excitations in
ferromagnets, have attracted a lot of attention recently. Skyrmionics is an
attempt to use magnetic skyrmions as information carriers in next generation
spintronic devices. Proposals of manipulations and operations of skyrmions are
highly desired. Here, we show that the conversion, duplication and merging of
isolated skyrmions with different chirality and topology are possible all in
one system. We also demonstrate the conversion of a skyrmion into another form
of a skyrmion, i.e., a bimeron. We design spin logic gates such as the AND and
OR gates based on manipulations of skyrmions. These results provide important
guidelines for utilizing the topology of nanoscale spin textures as information
carriers in novel magnetic sensors and spin logic devices.Comment: 17 pages, 6 figure
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