Effect of the Output of the System in Signal Detection

We analyze the consequences that the choice of the output of the system has in the efficiency of signal detection. It is shown that the signal and the signal-to-noise ratio (SNR), used to characterize the phenomenon of stochastic resonance, strongly depend on the form of the output. In particular, the SNR may be enhanced for an adequate output.Comment: 4 pages, RevTex, 6 PostScript figure

More Scalable LTL Model Checking via Discovering Design-Space Dependencies (D3)

Modern system design often requires comparing several models over a large design space. Different models arise out of a need to weigh different design choices, to check core capabilities of versions with varying features, or to analyze a future version against previous ones. Model checking can compare different models; however, applying model checking off-the-shelf may not scale due to the large size of the design space for today’s complex systems. We exploit relationships between different models of the same (or related) systems to optimize the model-checking search. Our algorithm, D3 , preprocesses the design space and checks fewer model-checking instances, e.g., using nuXmv. It automatically prunes the search space by reducing both the number of models to check, and the number of LTL properties that need to be checked for each model in order to provide the complete model-checking verdict for every individual model-property pair. We formalize heuristics that improve the performance of D3 . We demonstrate the scalability of D3 by extensive experimental evaluation, e.g., by checking 1,620 real-life models for NASA’s NextGen air traffic control system. Compared to checking each model-property pair individually, D3 is up to 9.4 × faster

Static Analysis of Modularity of β-Reduction in the Hyperbalanced λ-Calculus

We investigate the degree of parallelism (or modularity) in the hyperbalanced ?-calculus, ?H, a subcalculus of ?-calculus containing all simply typable terms (up to a restricted ?-expansion). In technical terms, we study the family relation on redexes in ?H, and the contribution relation on redex-families, and show that the latter is a forest (as a partial order). This means that hyperbalanced ?-terms allow for maximal possible parallelism in computation. To prove our results, we use and further refine, for the case of hyperbalanced terms, some well known results concerning paths, which allow for static analysis of many fundamental properties of ß-reduction

Minimal Relative Normalization in Orthogonal Expression Reduction Systems

. In previous papers, the authors studied normalization relative to desirable sets S of `partial results', where it is shown that such sets must be stable. For example, the sets of normal forms, head-normal-forms, and weak head-normal-forms in the -calculus, are all stable. They showed that, for any stable S, S-needed reductions are S-normalizing. This paper continues the investigation into the theory of relative normalization. In particular, we prove existence of minimal normalizing reductions for regular stable sets of results. All the above mentioned sets are regular. We give a sufficient and necessary criterion for a normalizing reduction (w.r.t. a regular stable S) to be minimal. Finally, we establish a relationship between relative minimal and optimal reductions, revealing a conflict between minimality and optimality: for regular stable sets of results, a term need not possess a reduction that is minimal and optimal at the same time. 1 Introduction The Normalization Theorem in ..

Assume-guarantee validation for STE properties within an SVA environment

Symbolic Trajectory Evaluation is an industrial-strength verification method, based on symbolic simulation and abstraction, that has been highly successful in data path verification, especially microprocessor execution units. These correctness results are typically obtained under certain assumptions about how the verified hardware block's inputs are driven, as well as assumptions about the values of these inputs. For correct overall operation, the hardware environment within which the verified block resides is expected to satisfy these assumptions. We describe a translation of these proof assumptions into System Verilog Assertions. These are then used as checkers in dynamic validation of the hardware environment within which blocks verified by Symbolic Trajectory Evaluation operate. The result is a pragmatic assume-guarantee method that increases the quality and confidence in verification results, requires little or no modification to the Symbolic Trajectory Evaluation proofs, and leverages pre-existing dynamic validation infrastructure. © 2009 IEEE

Stable Computational Semantics of Conflict-free Rewrite Systems (Partial Orders with Duplication)

We study orderings ?S on reductions in the style of Lévy reflecting the growth of information w.r.t. (super)stable sets S of ‘values’ (such as head-normal forms or Böhm-trees). We show that sets of co-initial reductions ordered by ?S form finitary ?-algebraic complete lattices, and hence form computation and Scott domains. As a consequence, we obtain a relativized version of the computational semantics proposed by Boudol for term rewriting systems. Furthermore, we give a pure domain-theoretic characterization of the orderings ?S in the spirit of Kahn and Plotkin’s concrete domains. These constructions are carried out in the framework of Stable Deterministic Residual Structures, which are abstract reduction systems with an axiomatized residual relations on redexes, that model all orthogonal (or conflict-free) reduction systems as well as many other interesting computation structures