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Topic: Unbounded system

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In the News (Fri 19 Jul 19)

  Tag system - Wikipedia, the free encyclopedia
A tag system is a deterministic computational model created by Emil Leon Post in 1943 as a simple form of string rewriting system.
Note that unlike some alternative definitions of tag systems, the present one is such that the "output" of a computation may be encoded in the final word.
Cyclic tag systems were created by Matthew Cook under the employ of Stephen Wolfram, and were used in Cook's demonstration that the Rule 110 cellular automaton is universal.
en.wikipedia.org /wiki/Tag_system   (761 words)

 Survivability and Simulation
Survivability is defined as the ability of a system to fulfill its mission in the presence of attacks, failures and accidents.
A survivability architecture is an abstraction that specifies the critical characteristics required for mission survivability in an unbounded system.
These problems are aggravated in unbounded systems where the numbers of components are very large and a primary purpose of simulation is to accurately predict the global effects from local activities.
www.sei.cmu.edu /community/easel/survsimesl.html   (1759 words)

 Distributed computing - Wikipedia, the free encyclopedia
The main goal of a distributed computing system is to connect users and resources in a transparent, open, and scalable way.
Multicomputer systems can be homogeneous or heterogeneous: A homogeneous distributed system is one where all CPUs are similar and are connected by a single type of network.
A heterogeneous distributed system is made up of different kinds of computers, possibly with vastly differing memory sizes, processing power and even basic underlying architecture.
en.wikipedia.org /wiki/Distributed_computing   (1563 words)

 CERT® Coordination Center Research
Typically, for a system to survive, it must react to (and recover from) a damaging effect (e.g., the integrity of a database is compromised) long before the underlying cause is identified.
Unbounded systems are a significant component of today's computing environment and will play an even a larger role in the future.
The financial system’s survivability might be judged by using a composite measure of the disruption of stock trades or bank transactions (i.e., a measure of the disruption of essential services).
www.cert.org /research/tr13/97tr013chap01.html   (4241 words)

 1990 Abstracts of MCS Reports and Preprints
This system is the intrinsic version of the radially symmetric prescribed mean curvature equation and permits the study of certain generalized solutions of this equation.
Properties of the system of isentropic gas dynamics, especially the behavior of entropy, are analyzed and documented.
The Lax-Friedrichs approximations, the Godunov approximations, and the viscosity approximations to the Cauchy problem for the system are constructed; and a compactness framework for these approximations is established with the aid of the theory of compensated compactness.
www-fp.mcs.anl.gov /division/publications/abstracts/abstracts90.htm   (9819 words)

 Survivability: Protecting Your Critical Systems
Unbounded networks are characterized by distributed administrative control without central authority, limited visibility beyond the boundaries of local administration, and a lack of complete information about the entire network.
A system that assumes an overly defensive position because of the threat of an attack may significantly reduce its functionality and divert excessive resources to monitoring the environment and protecting system assets.
System is often used as a shorthand term for a system with the capability to fulfill a specified mission in the face of attacks, failures, or accidents.
www.cert.org /archive/html/protect-critical-systems.html   (5399 words)

 STSC CrossTalk - The Survivability Imperative: Protecting Critical Systems - Oct 2000   (Site not responding. Last check: 2007-10-23)
Because system performance in testing (and operation) depends totally on the usage to which it is subjected, an effective approach to survivable system testing is based on usage scenarios derived from usage models.
Lastly, system evolution is an inevitable necessity in response to users' requirements for new functions and intruders' increasing knowledge of system behavior and structure.
System survivability can be investigated and improved through the SNA method, and survivability can be integrated into system requirements on a par with functionality and performance.
www.stsc.hill.af.mil /crosstalk/2000/10/linger.html   (2955 words)

 A.Pnueli/J.Xu/L.Zuck:   (Site not responding. Last check: 2007-10-23)
We introduce the (0,1,infinity)-counter abstraction method by which a parameterized system of unbounded size is abstracted into a finite-state system.
Assuming that each process in the parameterized system is finite-state, the abstract variables are limited counters which count, for each local state s of a process, the number of processes which currently are in local state s.
The emphasis of the paper is on the derivation of an adequate and sound set of fairness requirements (both weak and strong) which enable proofs of liveness properties of the abstract system, from which we can safely conclude a corresponding liveness property of the original parameterized system.
www.wisdom.weizmann.ac.il /~amir/PXZ02.htm   (186 words)

 SparkNotes: Presocratics: Anaximander of Miletus
In Anaximander's system the Unbounded (or apeiron) is both the source out of which everything derives and also the unifier within nature.
The Unbounded, we are told, is divine because it is deathless and indestructible.
The Unbounded steps in and restores the proper balance between them, making them "pay penalty and retribution." The cycles of night and day, and of the four seasons, are perfect examples of the forced equilibrium, and probably the examples Anaxagoras himself had in mind.
www.sparknotes.com /philosophy/presocratics/section2.rhtml   (1637 words)

 Evolving AI-Life by Natural Selection (Alastair Channon's Artificial Life)
Abstract: Bedau and Packard's evolutionary activity statistics are used to classify the evolutionary dynamics in Geb, a system designed to verify and extend theories behind the generation of evolutionary emergent systems.
The result is that, according to these statistics, Geb exhibits unbounded evolutionary activity, making it the first autonomous artificial system to pass this test.
This qualitative analysis indicates that evolution is unbounded in the system.
www.channon.net /alastair   (2074 words)

 [No title]
Because it is rarely the case that we know the properties of the molecular system with great accuracy, the calculated control field for any particular desired outcome of the system evolution will likely be sufficiently far from the true optimal field that much of the efficiency of guiding of the system evolution will be lost.
One promising approach is the study of Hamiltonian mappings in unbounded quantum systems, drawing on the experience gained from studies of such mappings in unbounded classical system.
Another promising approach is extension of the analysis of the properties and the significance of avoided crossings in the parametric dependence of the spectrum of states of a system, and improvement of the understanding of the representation of a complex system by random matrix theory.33 We propose carrying out studies of the types mentioned.
home.uchicago.edu /~mz12/indexpic/Research/Control.html   (751 words)

 On the complexity of recognizing the Hilbert basis of a linear Diophantine system   (Site not responding. Last check: 2007-10-23)
In automated deduction, the Hilbert basis of a corresponding system serves to compute the minimal complete set of associative-commutative unifiers, whereas in integer programming the Hilbert bases are tightly connected to integer polyhedra and to the notion of total dual integrality.
We show that the problem has a pseudopolynomial algorithm if the number of equations in the system is fixed, but it is coNP-complete in the strong sense if the given system is unbounded.
Moreover, we show that, from the complexity standpoint, it is not important to know the underlying homogeneous linear Diophantine system when we ask whether a given set of vectors constitutes a Hilbert basis.
www.lix.polytechnique.fr /~hermann/publications/recog-abs.html   (207 words)

 [No title]
This is true no matter whether this interaction is accounted for by the Breit potential, by an external magnetic field which is chosen to minimize the energy, or by the quantized radiation field.
In contrast to most other models, where the collapse of the system, if it occurs, is due to the attraction of electrons and nuclei \cite{Liebetal1986, LiebLoss1986, LiebYau1988, Loss1997} (there would be no collapse without this interaction), the instability here is due to the attraction of parallel currents.
The energy of this system is unbounded from below if $N\alpha^{3/2}$ is large, $\alpha$ being the fine structure constant, even if the vector potential is restricted to lie in a two parameter class \(\{\gamma\vA_0(\delta\vx):\gamma,\delta\in \R_+\}\) where $\vA_0$ is fixed and obeys a weak condition requiring not much more than $\vA_0\not\equiv 0$.
www.ma.utexas.edu /mp_arc/html/papers/98-719   (3566 words)

 The Feature System
The Feature System was developed by Professor Jesse D. Jennings, University of Utah, to systematize the complex process of archaeological excavation.
The ISU feature system carries Jennings' original concept over into computerized analyses, and extends a system intended for field excavation into the laboratory as the most effective means of documenting data analysis.
The essence of the feature system is that it is flexible, yet systematic, and capable of handling complex problems arising in the course of normal archaeological excavation.
imnh.isu.edu /digitalatlas/arch/ArchDef/manfeat.htm   (1043 words)

 Caltech Earthquake Engineering Research Laboratory Technical Reports - The Dynamic response of bilinear hysteretic ...
In the case of the one degree of freedom system exact steady state solutions are obtained for both square wave and trigonometric excitation.
An approximate steady state theory for the one degree of freedom system is investigated and on the basis of this theory it is found that the system is stable and possesses a single locus of vertical tangency.
The response of the one degree of freedom system to transient excitation of finite duration is also examined and it is noted that certain rather general conclusions may be made about the final state of the system without reference to the specific time history of the excitation.
caltecheerl.library.caltech.edu /293   (315 words)

 Dimitrov Voulov, Dimitrov Bainov: Asymptotic stability for a homogeneous singularly perturbed system of differential ...   (Site not responding. Last check: 2007-10-23)
Dimitrov Voulov, Dimitrov Bainov: Asymptotic stability for a homogeneous singularly perturbed system of differential equations with unbounded delay
Asymptotic stability for a homogeneous singularly perturbed system of differential equations with unbounded delay.
A.I.).— On asymptotic stability of systems with after-effect containing a small parameter as coefficient of the derivative, Prikl.
www.numdam.org /numdam-bin/item?id=AFST_1993_6_2_1_97_0   (280 words)

 The Efficient Generation of Cryptographic Confusion Sequences
Thus, proving that a sequence is non-random seemingly corresponds to the impossible task of "proving a negative" in an unbounded system.
Even simple integer arithmetic represents a fairly complex system at the binary gate level [e.g., 2: 23]; perhaps systems based on integer arithmetic are inherently complex (even the successful period analysis of the simple Additive RNG seems rather difficult [114]).
It would certainly be a benefit for system builders if the mathematicians, as part of the original work, would define a set of tests which would be sufficient to completely validate the implementation of their mathematical model.
www.ciphersbyritter.com /ARTS/CRNG2ART.HTM   (17722 words)

 Chapter 7   (Site not responding. Last check: 2007-10-23)
A system’s input requirements are, to a major extent, driven by its ___________ requirements.
An unbounded system is one in which the operational extent has been carefully defined and limited.
The system’s ___________ requirements are, to a major extent, driven by its output requirements.
www.westol.com /martzr/cpt_235/chap_7.htm   (2026 words)

 Scientific American: Survival in an Insecure World   (Site not responding. Last check: 2007-10-23)
The tapestries of machines that control transportation, banking, the power grid and virtually anything connected to the Internet are all unbounded systems, observes CERT researcher David A. Fisher: "No one, not even the owner, has complete and precise knowledge of the topology or state of the system.
For Fisher, the most pressing question is how to design systems that, although they are unbounded and thus inherently insecure, have "survivability." That means that even if they are damaged, they will still manage to fulfill their central function--sometimes sacrificing components, if necessary.
Fisher decided a new language was necessary when he started studying the mathematics of the cascade effects that dominate unbounded systems.
www.sciam.com /print_version.cfm?articleID=0001D65F-1318-1CD4-B4A8809EC588EEDF   (1244 words)

 Evaluation of the Current Density
To investigate the transport properties of a quantum system one must generally evaluate the current flow through the system, and this requires that one examine systems that are out of thermal equilibrium.
A common situation, in both experimental apparatus and technological systems, is that one has two (or more) physically large regions densely populated with electrons in which the current density is low, coupled by a smaller region through which the current density is much larger.
It is convenient to regard the large regions as ``electron reservoirs'' within which the electrons are all in equilibrium with a constant temperature and Fermi level, and which are so large that the current flow into or out of the smaller ``device'' represents a negligible perturbation.
www.utdallas.edu /~frensley/technical/qtrans/node6.html   (1216 words)

They are adopted according to the perceptions and understanding of the application and its domain at the time of implementation and are embedded in the system to bridge the gap but the real world is always changing.
This conclusion is supported by observations made during the FEAST and other studies and suggests that evolving software eventually, reaches a condition where, from an economic point of view at least, replacement is indicated.
The simplest is associated with the fact that there is a gap between the potentially unbounded E-type application and its real world operational domain and the finite system developed with finite resources in finite time to address a constrained application in a constrained domain.
www.csis.ul.ie /Modules/CS5122/A1/Group3/Law7.htm   (672 words)

 [No title]
This description includes the systems from which the activity originated and those targeted, an assessment of the techniques used by the intruder, the impact of the activity on the organization, and any forensic evidence discovered.
The systems represented by this class are categorized according to the role they played in the incident through the category attribute.
The System was an intermediary in the attack.
www.faqs.org /ftp/internet-drafts/draft-ietf-inch-iodef-04.txt   (8676 words)

 Papers - Windows NT '97
It was further clear from the consultation process that real-time extensions to the system should conform as closely as possible to the standard interfaces of the host OS.
The benefit to this approach is that all real time system activities are captured as real time threads, which provides a simple, coherent approach to setting priority across the real time subsystem, and allows for a more robust and verifiable implementation of the subsystem.
The NT system objects are those objects to which the RTSS processes have remote access.
www.usenix.org /publications/library/proceedings/usenix-nt97/full_papers/carpenter/carpenter_html/carpenter.html   (2497 words)

 Calculating Metrical Structure
My own assessment, however, is that once mechanisms are added to deal with unbounded, quantity sensitive and lexical stress systems, that its initial apparent restrictiveness will give way to a theory at least as rich in devices as the present one is.
Let us assume, at least as a heuristic (Elan!), that in unbounded systems words without marked syllables will indicate which side of the foot is the head.
This system is the mirror image of Moses-Columbian, which has three degrees of lexical weight, strong, alternating and weak.
www.ling.udel.edu /idsardi/cuny/cuny1.html   (4674 words)

 [No title]   (Site not responding. Last check: 2007-10-23)
We present efficient methods for analyzing the counterpart fluid system and show a dynamic programming procedure to devise an optimal QCS configuration for the fluid system.
If unbounded intermediate buffers are allowed, then the steady state performance of the discrete system and that of its fluid counterpart coincide.
In many other cases, a near optimal dispatching policy for the discrete system can be obtained from the fluid one.
www.math.technion.ac.il /~techm/20020325123020020325rav   (236 words)

 What Does Negative Temperature Mean?   (Site not responding. Last check: 2007-10-23)
Not all systems have the property that the entropy increases monotonically with energy.
In some cases, as energy is added to the system, the number of available microstates, or configurations, actually decreases for some range of energies.
So we have created a system where, as we add more and more energy, temperature starts off positive, approaches positive infinity as maximum entropy is approached, with half of all spins up.
math.ucr.edu /home/baez/physics/ParticleAndNuclear/neg_temperature.html   (1149 words)

If one seeks the eigenstates of a bounded system, the tridiagonal Hamiltonian may be readily diagonalized by standard numerical techniques.
This problem must be formulated in terms of the unbounded scattering states, and to do this we must modify the Hamiltonian matrix by incorporating the QTBM boundary conditions.
The matrix in (18) is just the denominator of the Green's function for Schrödinger's equation, in a space which has been augmented by adding the incomming traveling wave amplitudes.
www.utdallas.edu /eecs/ee/frensley/technical/nanomes91/node3.html   (555 words)

 Cancer and Wisdom of the Body: Cellular Automata
Although the system is bounded it seems that the same holds also for an unbounded system.
As the system converges  its members become wider, and the probability p1 of resource accumulation rises.
5 As the system converges   movement of its members becomes more and more sluggish, and  their probability p2  to meet declines.
www.what-is-cancer.com /papers/ca1/ca159.htm   (384 words)

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