149,986 research outputs found
Robustness-by-Construction Synthesis: Adapting to the Environment at Runtime
While most of the current synthesis algorithms only focus on
correctness-by-construction, ensuring robustness has remained a challenge.
Hence, in this paper, we address the robust-by-construction synthesis problem
by considering the specifications to be expressed by a robust version of Linear
Temporal Logic (LTL), called robust LTL (rLTL). rLTL has a many-valued
semantics to capture different degrees of satisfaction of a specification,
i.e., satisfaction is a quantitative notion.
We argue that the current algorithms for rLTL synthesis do not compute
optimal strategies in a non-antagonistic setting. So, a natural question is
whether there is a way of satisfying the specification "better" if the
environment is indeed not antagonistic. We address this question by developing
two new notions of strategies. The first notion is that of adaptive strategies,
which, in response to the opponent's non-antagonistic moves, maximize the
degree of satisfaction. The idea is to monitor non-optimal moves of the
opponent at runtime using multiple parity automata and adaptively change the
system strategy to ensure optimality. The second notion is that of strongly
adaptive strategies, which is a further refinement of the first notion. These
strategies also maximize the opportunities for the opponent to make non-optimal
moves. We show that computing such strategies for rLTL specifications is not
harder than the standard synthesis problem, e.g., computing strategies with LTL
specifications, and takes doubly-exponential time.Comment: 32 pages, 3 figure
Synthesis and Optimization of Reversible Circuits - A Survey
Reversible logic circuits have been historically motivated by theoretical
research in low-power electronics as well as practical improvement of
bit-manipulation transforms in cryptography and computer graphics. Recently,
reversible circuits have attracted interest as components of quantum
algorithms, as well as in photonic and nano-computing technologies where some
switching devices offer no signal gain. Research in generating reversible logic
distinguishes between circuit synthesis, post-synthesis optimization, and
technology mapping. In this survey, we review algorithmic paradigms ---
search-based, cycle-based, transformation-based, and BDD-based --- as well as
specific algorithms for reversible synthesis, both exact and heuristic. We
conclude the survey by outlining key open challenges in synthesis of reversible
and quantum logic, as well as most common misconceptions.Comment: 34 pages, 15 figures, 2 table
Design Optimization of Time- and Cost-Constrained Fault-Tolerant Embedded Systems with Checkpointing and Replication
We present an approach to the synthesis of fault-tolerant hard real-time systems for safety-critical applications. We use checkpointing with rollback recovery and active replication for tolerating transient faults. Processes and communications are statically scheduled. Our synthesis approach decides the assign-ment of fault-tolerance policies to processes, the optimal place-ent of checkpoints and the mapping of processes to processors such that multiple transient faults are tolerated and the timing con-straints of the application are satisfied. We present several design optimization approaches which are able to find fault-tolerant im-plementations given a limited amount of resources. The developed algorithms are evaluated using extensive experiments, including a real-life example
A Study of Optimal 4-bit Reversible Toffoli Circuits and Their Synthesis
Optimal synthesis of reversible functions is a non-trivial problem. One of
the major limiting factors in computing such circuits is the sheer number of
reversible functions. Even restricting synthesis to 4-bit reversible functions
results in a huge search space (16! {\approx} 2^{44} functions). The output of
such a search alone, counting only the space required to list Toffoli gates for
every function, would require over 100 terabytes of storage. In this paper, we
present two algorithms: one, that synthesizes an optimal circuit for any 4-bit
reversible specification, and another that synthesizes all optimal
implementations. We employ several techniques to make the problem tractable. We
report results from several experiments, including synthesis of all optimal
4-bit permutations, synthesis of random 4-bit permutations, optimal synthesis
of all 4-bit linear reversible circuits, synthesis of existing benchmark
functions; we compose a list of the hardest permutations to synthesize, and
show distribution of optimal circuits. We further illustrate that our proposed
approach may be extended to accommodate physical constraints via reporting
LNN-optimal reversible circuits. Our results have important implications in the
design and optimization of reversible and quantum circuits, testing circuit
synthesis heuristics, and performing experiments in the area of quantum
information processing.Comment: arXiv admin note: substantial text overlap with arXiv:1003.191
The Synthesis and Analysis of Stochastic Switching Circuits
Stochastic switching circuits are relay circuits that consist of stochastic
switches called pswitches. The study of stochastic switching circuits has
widespread applications in many fields of computer science, neuroscience, and
biochemistry. In this paper, we discuss several properties of stochastic
switching circuits, including robustness, expressibility, and probability
approximation.
First, we study the robustness, namely, the effect caused by introducing an
error of size \epsilon to each pswitch in a stochastic circuit. We analyze two
constructions and prove that simple series-parallel circuits are robust to
small error perturbations, while general series-parallel circuits are not.
Specifically, the total error introduced by perturbations of size less than
\epsilon is bounded by a constant multiple of \epsilon in a simple
series-parallel circuit, independent of the size of the circuit.
Next, we study the expressibility of stochastic switching circuits: Given an
integer q and a pswitch set S=\{\frac{1}{q},\frac{2}{q},...,\frac{q-1}{q}\},
can we synthesize any rational probability with denominator q^n (for arbitrary
n) with a simple series-parallel stochastic switching circuit? We generalize
previous results and prove that when q is a multiple of 2 or 3, the answer is
yes. We also show that when q is a prime number larger than 3, the answer is
no.
Probability approximation is studied for a general case of an arbitrary
pswitch set S=\{s_1,s_2,...,s_{|S|}\}. In this case, we propose an algorithm
based on local optimization to approximate any desired probability. The
analysis reveals that the approximation error of a switching circuit decreases
exponentially with an increasing circuit size.Comment: 2 columns, 15 page
Energy-Efficient Multi-View Video Transmission with View Synthesis-Enabled Multicast
Multi-view videos (MVVs) provide immersive viewing experience, at the cost of
heavy load to wireless networks. Except for further improving viewing
experience, view synthesis can create multicast opportunities for efficient
transmission of MVVs in multiuser wireless networks, which has not been
recognized in existing literature. In this paper, we would like to exploit view
synthesis-enabled multicast opportunities for energy-efficient MVV transmission
in a multiuser wireless network. Specifically, we first establish a
mathematical model to characterize the impact of view synthesis on multicast
opportunities and energy consumption. Then, we consider the optimization of
view selection, transmission time and power allocation to minimize the weighted
sum energy consumption for view transmission and synthesis, which is a
challenging mixed discrete-continuous optimization problem. We propose an
algorithm to obtain an optimal solution with reduced computational complexity
by exploiting optimality properties. To further reduce computational
complexity, we also propose two low-complexity algorithms to obtain two
suboptimal solutions, based on continuous relaxation and Difference of Convex
(DC) programming, respectively. Finally, numerical results demonstrate the
advantage of the proposed solutions.Comment: 22 pages, 6 figures, to be published in GLOBECOM 201
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