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1.
Agent Communication Languages (ACLs) have been developed to provide a way for agents to communicate with each other supporting
cooperation in Multi-Agent Systems (MAS). In the past few years many ACLs have been proposed for MAS and new standards are
emerging such as the ACL developed by the Foundation for Intelligent Physical Agents (FIPA). Despite these efforts, an important
issue in the research on ACLs is still open and concerns how these languages should deal with failures of agents in asynchronous MAS. The Fault Tolerant Agent Communication Language (
-
) presented in this paper addresses this issue dealing with crash failures of agents.
-
provides high-level communication primitives which support a fault-tolerant anonymous interaction protocol designed for open
MAS. We present a formal semantics for
-
and a formal specification of the underlying agent architecture. This formal framework allows us to prove that the ACL satisfies
a set of well defined knowledge-level programming requirements. To illustrate the language features we show how
-
can be effectively used to write high-level executable specifications of fault tolerant protocols, such as the Contract Net
one. 相似文献
2.
Hierarchical matrices (
-matrices) approximate matrices in a data-sparse way, and the approximate arithmetic for
-matrices is almost optimal. In this paper we present an algebraic approach for constructing
-matrices which combines multilevel clustering methods with
-matrix arithmetic to compute the
-inverse,
-LU, and the
-Cholesky factors of a matrix. Then the
-inverse,
-LU or
-Cholesky factors can be used as preconditioners in iterative methods to solve systems of linear equations. The numerical
results show that this method is efficient and greatly speeds up convergence compared to other approaches, such as JOR or
AMG, for solving some large, sparse linear systems, and is comparable to other
-matrix constructions based on Nested Dissection. 相似文献
3.
We construct a linear interval system Ax = b with a 4 × 4 interval matrix whose all proper interval coefficients (there are also some noninterval ones) are of the form [–, ]. It is proved that for each > 0, the interval hull
and interval hull of the midpoint preconditioned system
satisfy
and
, hence midpoint preconditioning produces a 100% overestimation of
independently of in this case. The example was obtained as a result of an extensive MATLAB search. 相似文献
4.
Coupling and self-stabilization 总被引:1,自引:0,他引:1
A randomized self-stabilizing algorithm
is an algorithm that, whatever the initial configuration is, reaches a set
of М legal configurations} in finite time with probability 1. The proof of convergence towards
is generally done by exhibiting a potential function
, which measures the “vertical” distance of any configuration to
, such that
decreases with non-null probability at each step of
. We propose here a method, based on the notion of coupling, which makes use of a “horizontal” distance
between any pair of configurations, such that
decreases in expectation at each step of
. In contrast with classical methods, our coupling method does not require the knowledge of
. In addition to the proof of convergence, the method allows us to assess the convergence rate according to two different
measures. Proofs produced by the method are often simpler or give better upper bounds than their classical counterparts, as
examplified here on Herman's mutual exclusion and Iterated Prisoner's Dilemma algorithms in the case of cyclic graphs. 相似文献
6.
R. F. Streater 《Open Systems & Information Dynamics》2004,11(4):359-375
Let H0 be a selfadjoint operator such that Tr
is of trace class for some
, and let
denote the set of ε-bounded forms, i.e.,
for some
0 $$" align="middle" border="0">
. Let χ := Span
. Let
denote the underlying set of the quantum information manifold of states of the form
. We show that if Tr
,
Presented at the 36th Symposium on Mathematical Physics, ‘Open Systems & Quantum Information’, Toruń, Poland, June 9-12, 2004. 相似文献
1. | the map Φ,
| |
2. | The Orlicz space defined by Φ is the tangent space of at ρ0; its affine structure is defined by the (+1)-connection of Amari | |
3. | The subset of a ‘hood of ρ0, consisting of p-nearby states (those obeying for some 1$$" align="middle" border="0"> ) admits a flat affine connection known as the (-1) connection, and the span of this set is part of the cotangent space of | |
4. | These dual structures extend to the completions in the Luxemburg norms. |
7.
Eric Allender Anna Bernasconi Carsten Damm Joachim von zur Gathen Michael Saks Igor Shparlinski 《Computational Complexity》2003,12(1-2):23-47
We study various combinatorial complexity measures of
Boolean functions related to some natural arithmetic problems about
binary polynomials, that is, polynomials over
.
In particular, we consider
the Boolean function deciding whether a given polynomial over
is squarefree. We obtain an exponential lower bound on the size of a
decision tree for this function, and derive an asymptotic formula, having
a linear main term, for its average sensitivity. This allows us to estimate
other complexity characteristics such as the formula size, the average decision
tree depth and the degrees of exact and approximative polynomial
representations of this function. Finally, using a different method, we
show that testing squarefreeness and irreducibility of polynomials over
cannot be done in
for any odd prime p. Similar results are
obtained for deciding coprimality of two polynomials over
as well. 相似文献
8.
Abstract We obtain a multivariate extension of a classical result of Schoenberg on cardinal spline interpolation. Specifically, we
prove the existence of a unique function in
, polyharmonic of order p on each strip
,
, and periodic in its last n variables, whose restriction to the parallel hyperplanes
,
, coincides with a prescribed sequence of n-variate periodic data functions satisfying a growth condition in
. The constructive proof is based on separation of variables and on Micchelli’s theory of univariate cardinal
-splines.
Keywords: cardinal
-splines, polyharmonic functions, multivariable interpolation
Mathematics Subject Classification (2000): 41A05, 41A15, 41A63 相似文献
9.
10.
The Sum of D Small-Bias Generators Fools Polynomials of Degree D 总被引:1,自引:1,他引:0
Emanuele Viola 《Computational Complexity》2009,18(2):209-217
11.
12.
Remco Duits Michael Felsberg Gösta Granlund Bart ter Haar Romeny 《International Journal of Computer Vision》2007,72(1):79-102
Inspired by the early visual system of many mammalians we consider the construction of-and reconstruction from- an orientation
score
as a local orientation representation of an image,
. The mapping
is a wavelet transform
corresponding to a reducible representation of the Euclidean motion group onto
and oriented wavelet
. This wavelet transform is a special case of a recently developed generalization of the standard wavelet theory and has the
practical advantage over the usual wavelet approaches in image analysis (constructed by irreducible representations of the
similitude group) that it allows a stable reconstruction from one (single scale) orientation score. Since our wavelet transform
is a unitary mapping with stable inverse, we directly relate operations on orientation scores to operations on images in a
robust manner.
Furthermore, by geometrical examination of the Euclidean motion group
, which is the domain of our orientation scores, we deduce that an operator Φ on orientation scores must be left invariant
to ensure that the corresponding operator
on images is Euclidean invariant. As an example we consider all linear second order left invariant evolutions on orientation
scores corresponding to stochastic processes on G. As an application we detect elongated structures in (medical) images and automatically close the gaps between them.
Finally, we consider robust orientation estimates by means of channel representations, where we combine robust orientation
estimation and learning of wavelets resulting in an auto-associative processing of orientation features. Here linear averaging
of the channel representation is equivalent to robust orientation estimation and an adaptation of the wavelet to the statistics
of the considered image class leads to an auto-associative behavior of the system.
The Netherlands Organization for Scientific Research is gratefully acknowledged for financial support. This work has been
supported by EC Grant IST-2003-004176 COSPAL. 相似文献
13.
Escape analysis of object-oriented languages approximates the set of objects which do not escape from a given context. If we take a method as context, the non-escaping objects can be allocated on its activation stack;
if we take a thread, Java synchronisation locks on such objects are not needed. In this paper, we formalise a basic escape
domain
as an abstract interpretation of concrete states, which we then refine into an abstract domain
which is more concrete than
and, hence, leads to a more precise escape analysis than
. We provide optimality results for both
and
, in the form of Galois insertions from the concrete to the abstract domains and of optimal abstract operations. The Galois
insertion property is obtained by restricting the abstract domains to those elements which do not contain garbage, by using an abstract garbage collector. Our implementation of
is hence an implementation of a formally correct escape analyser, able to detect the stack allocatable creation points of
Java (bytecode) applications. 相似文献
14.
15.
Edmund Clarke Daniel Kroening Joël Ouaknine Ofer Strichman 《International Journal on Software Tools for Technology Transfer (STTT)》2005,7(2):174-183
We describe several observations regarding the completeness and the complexity of bounded model checking and propose techniques to solve some of the associated computational challenges. We begin by defining the completeness threshold (
) problem: for every finite model M and an LTL property , there exists a number
such that if there is no counterexample to in M of length
or less, then M
. Finding this number, if it is sufficiently small, offers a practical method for making bounded model checking complete. We describe how to compute an overapproximation to
for a general LTL property using Büchi automata, following the Vardi–Wolper LTL model checking framework. This computation is based on finding the initialized diameter and initialized recurrence-diameter (the longest loop-free path from an initial state) of the product automaton. We show a method for finding a recurrence diameter with a formula of size O(klogk) (or O(k(logk)2) in practice), where k is the attempted depth, which is an improvement compared to the previously known method that requires a formula of size in O(k2). Based on the value of
, we prove that the complexity of standard SAT-based BMC is doubly exponential and that, consequently, there is a complexity gap of an exponent between this procedure and standard LTL model checking. We discuss ways to bridge this gap. 相似文献
16.
Richardson splitting applied to a consistent system of linear equations Cx = b with a singular matrix C yields to an iterative method xk+1 = Axk + b where A has the eigenvalue one. It is known that each sequence of iterates is convergent to a vector x* = x* (x0) if and only if A is semi-convergent. In order to enclose such vectors we consider the corresponding interval iteration
with (|[A]|) = 1 where |[A]| denotes the absolute value of the interval matrix [A]. If |[A]| is irreducible we derive a necessary and sufficient criterion for the existence of a limit
of each sequence of interval iterates. We describe the shape of
and give a connection between the convergence of (
) and the convergence of the powers
of [A].Dedicated to Professor G. Mae on the occasion of his 65th birthday 相似文献
17.
The Still-Life problem is challenging for CP techniques because the basic constraints of the game of Life are loose and give
poor propagation for Still-Life. In this paper, we show how ad hoc global
constraints can be customized to construct various models to provide much stronger propagation with CP solvers. Since we
use custom ad hoc constraints of high arity where the number of tuples to define the constraint are large, the actual constraint
representation becomes important to avoid excessive space consumption. We demonstrate how to use BDDs to construct good representations
for the
constraint which is critical for efficiency. Our results seem comparable to hybrid CP/IP models even though we are only using
propagation albeit on ad hoc global constraints. This paper shows an extensive example of how to systematically build models
using different kinds of ad hoc constraints. It also demonstrates the solving potential of ad hoc global constraints. 相似文献
18.
Martin Ziegler 《Theory of Computing Systems》2007,41(1):177-206
By the sometimes so-called Main Theorem of Recursive Analysis, every computable real function is necessarily continuous. We
wonder whether and which kinds of hypercomputation allow for the effective evaluation of also discontinuous
. More precisely the present work considers the following three super-Turing notions of real function computability: - relativized
computation; specifically given oracle access to the Halting Problem
or its jump
; - encoding input
and/or output y = f(x) in weaker ways also related to the Arithmetic Hierarchy; - nondeterministic computation. It turns
out that any
computable in the first or second sense is still necessarily continuous whereas the third type of hypercomputation provides
the required power to evaluate for instance the discontinuous Heaviside function. 相似文献
19.
20.
In 1999 Nakano, Olariu, and Schwing in [20], they showed that the permutation routing of n items pretitled on a mobile ad hoc network (MANET for short) of p stations (p known) and k channels (MANET{(n, p, k)) with k < p, can be carried out in
broadcast rounds if k p and if each station has a
-memory locations. And if k
and if each station has a
-memory locations, the permutations of these n pretitled items can be done also in
broadcast rounds. They used two assumptions: first they suppose that each station of the mobile ad hoc network has an identifier beforehand. Secondly, the stations are partitioned into k groups such that each group has
stations, but it was not shown how this partition can be obtained. In this paper, the stations have not identifiers beforehand and p is unknown. We develop a protocol which first names the stations, secondly gives the value of p, and partitions stations in groups of
stations. Finally we show that the permutation routing problem can be solved on it in
broadcast rounds in the worst case. It can be solved in
broadcast rounds in the better case. Note that our approach does not impose any restriction on k. 相似文献