521 research outputs found
The Gambier Mapping, Revisited
We examine critically the Gambier equation and show that it is the generic
linearisable equation containing, as reductions, all the second-order equations
which are integrable through linearisation. We then introduce the general
discrete form of this equation, the Gambier mapping, and present conditions for
its integrability. Finally, we obtain the reductions of the Gambier mapping,
identify their integrable forms and compute their continuous limits.Comment: 11 pages, no figures, to be published in Physica
A new approach for diagnosability analysis of Petri nets using Verifier Nets
In this paper, we analyze the diagnosability properties of labeled Petri nets. We consider the standard notion of diagnosability of languages, requiring that every occurrence of an unobservable fault event be eventually detected, as well as the stronger notion of diagnosability in K steps, where the detection must occur within a fixed bound of K event occurrences after the fault. We give necessary and sufficient conditions for these two notions of diagnosability for both bounded and unbounded Petri nets and then present an algorithmic technique for testing the conditions based on linear programming. Our approach is novel and based on the analysis of the reachability/coverability graph of a special Petri net, called Verifier Net, that is built from the Petri net model of the given system. In the case of systems that are diagnosable in K steps, we give a procedure to compute the bound K. To the best of our knowledge, this is the first time that necessary and sufficient conditions for diagnosability and diagnosability in K steps of labeled unbounded Petri nets are presented
Discrete and Continuous Linearizable Equations
We study the projective systems in both continuous and discrete settings.
These systems are linearizable by construction and thus, obviously, integrable.
We show that in the continuous case it is possible to eliminate all variables
but one and reduce the system to a single differential equation. This equation
is of the form of those singled-out by Painlev\'e in his quest for integrable
forms. In the discrete case, we extend previous results of ours showing that,
again by elimination of variables, the general projective system can be written
as a mapping for a single variable. We show that this mapping is a member of
the family of multilinear systems (which is not integrable in general). The
continuous limit of multilinear mappings is also discussed.Comment: Plain Tex file, 14 pages, no figur
Symmetries of Discrete Dynamical Systems Involving Two Species
The Lie point symmetries of a coupled system of two nonlinear
differential-difference equations are investigated. It is shown that in special
cases the symmetry group can be infinite dimensional, in other cases up to 10
dimensional. The equations can describe the interaction of two long molecular
chains, each involving one type of atoms.Comment: 40 pages, no figures, typed in AMS-LaTe
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