90,254 research outputs found
Stability Analysis of Jump-Linear Systems Driven by Finite-State Machines with Markovian Inputs
A control system with a fault recovery mechanism in the feedback loop and with faults occurring in a non-deterministic manner can be modeled as a class of hybrid systems, i.e., a dynamical system switched by a finite-state machine or an automaton. When the plant and controller are linear, such a system can be modeled as a jump-linear system driven by a finite-state machine with a random input process. Such fault recovery mechanisms are found in flight control systems and distributed control systems with communication networks. In these critical applications, closed-loop stability of the system in the presence of fault recoveries becomes an important issue.
Finite-state machines as mathematical constructs are widely used by computer scientists to model and analyze algorithms. In particular, fault recovery mechanisms that are implemented in hardware with logic based circuits and finite memory can be modeled appropriately with finite-state machines. In this thesis, mathematical tools are developed to determine the mean-square stability of a closed-loop system, modeled as a jump-linear system in series with a finite-state machine driven by a random process. The random input process is in general assumed to be any r-th order Markov process, where r ≥ 0. While stability tests for a jump-linear system with a Markovian switching rule are well known, the main contribution of the present work arises from the fact that output of a finite-state machine driven by a Markov process is in general not Markovian. Therefore, new stability analysis tools are provided for this class of systems and demonstrated through Monte Carlo simulations
Checking Presence Reachability Properties on Parameterized Shared-Memory Systems
We consider the verification of distributed systems composed of an arbitrary
number of asynchronous processes. Processes are identical finite-state machines
that communicate by reading from and writing to a shared memory. Beyond the
standard model with finitely many registers, we tackle round-based
shared-memory systems with fresh registers at each round. In the latter model,
both the number of processes and the number of registers are unbounded, making
verification particularly challenging. The properties studied are generic
presence reachability objectives, which subsume classical questions such as
safety or synchronization by expressing the presence or absence of processes in
some states. In the more general round-based setting, we establish that the
parameterized verification of presence reachability properties is
PSPACE-complete. Moreover, for the roundless model with finitely many
registers, we prove that the complexity drops down to NP-complete and we
provide several natural restrictions that make the problem solvable in
polynomial time.Comment: 27 pages, 6 figure
Checking Presence Reachability Properties on Parameterized Shared-Memory Systems
We consider the verification of distributed systems composed of an arbitrary number of asynchronous processes. Processes are identical finite-state machines that communicate by reading from and writing to a shared memory. Beyond the standard model with finitely many registers, we tackle round-based shared-memory systems with fresh registers at each round. In the latter model, both the number of processes and the number of registers are unbounded, making verification particularly challenging. The properties studied are generic presence reachability objectives, which subsume classical questions such as safety or synchronization by expressing the presence or absence of processes in some states. In the more general round-based setting, we establish that the parameterized verification of presence reachability properties is PSPACE-complete. Moreover, for the roundless model with finitely many registers, we prove that the complexity drops down to NP-complete and we provide several natural restrictions that make the problem solvable in polynomial time
Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C
We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples
Consistency of Feature Markov Processes
We are studying long term sequence prediction (forecasting). We approach this
by investigating criteria for choosing a compact useful state representation.
The state is supposed to summarize useful information from the history. We want
a method that is asymptotically consistent in the sense it will provably
eventually only choose between alternatives that satisfy an optimality property
related to the used criterion. We extend our work to the case where there is
side information that one can take advantage of and, furthermore, we briefly
discuss the active setting where an agent takes actions to achieve desirable
outcomes.Comment: 16 LaTeX page
Towards a Church-Turing-Thesis for Infinitary Computations
We consider the question whether there is an infinitary analogue of the
Church-Turing-thesis. To this end, we argue that there is an intuitive notion
of transfinite computability and build a canonical model, called Idealized
Agent Machines (s) of this which will turn out to be equivalent in
strength to the Ordinal Turing Machines defined by P. Koepke
Structural Drift: The Population Dynamics of Sequential Learning
We introduce a theory of sequential causal inference in which learners in a
chain estimate a structural model from their upstream teacher and then pass
samples from the model to their downstream student. It extends the population
dynamics of genetic drift, recasting Kimura's selectively neutral theory as a
special case of a generalized drift process using structured populations with
memory. We examine the diffusion and fixation properties of several drift
processes and propose applications to learning, inference, and evolution. We
also demonstrate how the organization of drift process space controls fidelity,
facilitates innovations, and leads to information loss in sequential learning
with and without memory.Comment: 15 pages, 9 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/sdrift.ht
High-Performance Architecture for Binary-Tree-Based Finite State Machines
A binary-tree-based finite state machine (BT-FSM)
is a state machine with a 1-bit input signal whose state transition
graph is a binary tree. BT-FSMs are useful in those
application areas where searching in a binary tree is required,
such as computer networks, compression, automatic control, or
cryptography. This paper presents a new architecture for implementing
BT-FSMs which is based on the model finite virtual state
machine (FVSM). The proposed architecture has been compared
with the general FVSM and conventional approaches by using
both synthetic test benches and very large BT-FSMs obtained
from a real application. In synthetic test benches, the average
speed improvement of the proposed architecture respect to the
best results of the other approaches achieves 41% (there are
some cases in which the speed is more than double). In the
case of the real application, the average speed improvement
achieves 155%
Quantum computation with devices whose contents are never read
In classical computation, a "write-only memory" (WOM) is little more than an
oxymoron, and the addition of WOM to a (deterministic or probabilistic)
classical computer brings no advantage. We prove that quantum computers that
are augmented with WOM can solve problems that neither a classical computer
with WOM nor a quantum computer without WOM can solve, when all other resource
bounds are equal. We focus on realtime quantum finite automata, and examine the
increase in their power effected by the addition of WOMs with different access
modes and capacities. Some problems that are unsolvable by two-way
probabilistic Turing machines using sublogarithmic amounts of read/write memory
are shown to be solvable by these enhanced automata.Comment: 32 pages, a preliminary version of this work was presented in the 9th
International Conference on Unconventional Computation (UC2010
- …