A geometrically random network of sensors is obtained by modeling sensors as random points in the unit disc equipped with a local sensing capability and the ability to communicate with other sensors in their vicinity....
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A geometrically random network of sensors is obtained by modeling sensors as random points in the unit disc equipped with a local sensing capability and the ability to communicate with other sensors in their vicinity. Node extinctions in the network representing the finite battery lifetimes of the sensors are modeled as a sequence of independent random variables governed by a common probability distribution parametrized by the sensing and communication radii of the sensor nodes. Following its establishment, the devolution of the network with time is characterized by the appearance first of isolated nodes, then the growth of sensory lacunae or dead spots in the sensor field, and, eventually, a breakdown in connectivity between survivors. It is shown that these phenomena occur very sharply in time, these phase transitions occurring at times characteristic of the underlying probability law governing lifetimes. More precisely, it is shown that as the number of sensors grows there exists a critical point in time determined solely by the lifetime distribution at which the number of emergent lacunae of a given size is asymptotically Poisson.
We consider the binomial random graph G(p) and determine a sharp threshold function for the edge-Ramsey property G(p) --> (C-l1,...,C-lr) for all l(1),...,l(r), where C-l denotes the cycle of length l. As determini...
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We consider the binomial random graph G(p) and determine a sharp threshold function for the edge-Ramsey property G(p) --> (C-l1,...,C-lr) for all l(1),...,l(r), where C-l denotes the cycle of length l. As deterministic consequences of our results, we prove the existence of sparse graphs having the above Ramsey property as well as the existence of infinitely many critical graphs with respect to the property above. (C) 1997 John Wiley & Sons, Ins.
This paper obtains explicit decomposition of threshold functions into bounded fan-in threshold functions. A small fan-in is important to satisfy technology constraints for large scale integration. By employing the con...
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This paper obtains explicit decomposition of threshold functions into bounded fan-in threshold functions. A small fan-in is important to satisfy technology constraints for large scale integration. By employing the concept of error in the threshold function, we are able to decompose functions in LT1 into a network of size O(n(c)/M-2) and depth O(log(2)n/logM) where n is the number of inputs of the function and M is the fan-in bound. The proposed construction enables one to trade-off the size and depth of the decomposition with the fan-in bound. Combined with the work on small weight threshold functions, this implies polynomial size, log(2) depth bounded fan-in decompositions for arbitrary threshold functions in LTd. These results compare favorably with the classical decomposition which has a size O(2(n-M)) and depth O(n-M). We also show that the decomposition size and depth can be significantly reduced by exploiting the relationships between the input weights. As examples of this strategy, we demonstrate an O(n(2)/M) size decomposition of the majority function and, O(n/M) size decompositions of an error tolerant pattern matching function and the comparison function. In all these examples, except for the first level, all other levels use only majority functions. (C) 2013 Elsevier Inc. All rights reserved.
A linear threshold element computes a function that is a sign of a weighted sum of the input variables. The best known lower bounds on the size of threshold circuits are for depth-2 circuits with small (polynomial-siz...
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A linear threshold element computes a function that is a sign of a weighted sum of the input variables. The best known lower bounds on the size of threshold circuits are for depth-2 circuits with small (polynomial-size) weights. However, in general, the weights are arbitrary integers and can be of exponential size in the number of input variables. Namely, obtaining progress in lower bounds for threshold circuits seems to be related to understanding the role of large weights. In the present literature, a distinction is made between the two extreme cases of linear threshold functions with polynomial-size weights, as opposed to those with exponential-size weights. Our main contributions are in devising two novel methods for constructing threshold functions with minimal weights and filling up the gap between polynomial and exponential weight growth by further refining the separation. Namely, we prove that the class of linear threshold functions with polynomial-size weights can be divided into subclasses according to the degree of the polynomial. In fact, we prove a more general result-that there exists a minimal weight linear threshold function for any arbitrary number of inputs and any weight size.
Motivated by the impact of fast algebraic attacks on stream ciphers, and recent constructions using a threshold function as main part of the filtering function, we study the fast algebraic immunity of threshold functi...
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Motivated by the impact of fast algebraic attacks on stream ciphers, and recent constructions using a threshold function as main part of the filtering function, we study the fast algebraic immunity of threshold functions. As a first result, we determine exactly the fast algebraic immunity of all majority functions in more than 8 variables. Then, For all n >= 8 and all threshold value between 1 and n we exhibit the fast algebraic immunity for most of the thresholds, and we determine a small range for the value related to the few remaining cases. Finally, provided m >= 2, we determine exactly the fast algebraic immunity of all threshold functions in 3 . 2(m) or 3 . 2(m) + 1 variables.
In this paper, we deal with encoding and enumerating threshold functions defined on n-dimensional binary inputs. The paper specifies situations in which the unique characterization of functions from a given class is p...
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In this paper, we deal with encoding and enumerating threshold functions defined on n-dimensional binary inputs. The paper specifies situations in which the unique characterization of functions from a given class is preserved by usage of an appropriate set of discrete moments. Moreover, sometimes such a characterization (coding) is optimal with respect to the number of necessary bit rate per coded function. By estimating the number of possible values of the discrete moments used, several upper bounds (for different classes of threshold functions) are derived, some of which are better than those previously known.
This paper examines the class of polynomial threshold functions using harmonic analysis and applies the results to derive lower bounds related to AC0 functions. A Boolean function is polynomial threshold if it can be ...
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This paper examines the class of polynomial threshold functions using harmonic analysis and applies the results to derive lower bounds related to AC0 functions. A Boolean function is polynomial threshold if it can be represented as the sign of a sparse polynomial (one that consists of a polynomial number of terms). The main result of this paper is that the class of polynomial threshold functions can be characterized using their spectral representation. In particular, it is proved that an n-variable Boolean function whose L1 spectral norm is bounded by a polynomial in n is a polynomial threshold function, while a Boolean function whose L infinity-1 spectral norm is not bounded by a polynomial in n is not a polynomial threshold function [J. Bruck, SIAM J. Discrete Math., 3 (1990), pp. 168-177]. The motivation is that the characterization of polynomial threshold functions can be applied to obtain upper and lower bounds on the complexity of computing with networks of linear threshold elements. In this paper results related to the complexity of computing AC0 functions are presented. More applications of the characterization theorem are presented in [J. Bruck, SIAM J. Discrete Math., 3 (1990), pp. 168-177] and [K. Y. Siu and J. Bruck, SIAM J. Discrete Math., 4 (1991), pp. 423-435].
Card-based cryptography is a variant of multi-party computation using physical cards like playing cards. There are two models on card-based cryptography, called public and private models. The public model assumes that...
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Card-based cryptography is a variant of multi-party computation using physical cards like playing cards. There are two models on card-based cryptography, called public and private models. The public model assumes that all operations are executed publicly, while the private model allows the players private operations called private permutations (PP, for short). Much of the existing card-based protocols were developed under the public model. Under the public model, 2n cards are necessary for every protocol with n-bit input since at least two cards are required to express a bit. In this paper, we propose n-bit input protocols with fewer than 2n cards by utilizing PP, which shows the power of PP. In particular, we show that a protocol for (n-bit input) threshold function can be realized with only n + 1 cards by reducing the threshold function to the majority voting. Toward this end, we first offer that two-bit input protocols for logic gates can be realized with fewer than four cards. Furthermore, we construct a new protocol for three-input majority voting with only four cards by observing the relationship between AND/OR operations. This protocol can be easily extended to more participants, and to the protocol for threshold functions.
A class of wavelet filtration algorithms with two-parameter threshold functions is considered. An algorithm is proposed for solving the problem of choosing two threshold values, which allows estimating their optimal v...
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A class of wavelet filtration algorithms with two-parameter threshold functions is considered. An algorithm is proposed for solving the problem of choosing two threshold values, which allows estimating their optimal values with acceptable accuracy.
We prove two main results on how arbitrary linear threshold functions over the n-dimensional Boolean hypercube can be approximated by simple threshold functions. Our first result shows that every n-variable threshold ...
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We prove two main results on how arbitrary linear threshold functions over the n-dimensional Boolean hypercube can be approximated by simple threshold functions. Our first result shows that every n-variable threshold function f is -close to a threshold function depending only on many variables, where denotes the total influence or average sensitivity of f. This is an exponential sharpening of Friedgut's well-known theorem (Friedgut in Combinatorica 18(1):474-483, 1998), which states that every Boolean function f is -close to a function depending only on many variables, for the case of threshold functions. We complement this upper bound by showing that many variables are required for -approximating threshold functions. Our second result is a proof that every n-variable threshold function is -close to a threshold function with integer weights at most This is an improvement, in the dependence on the error parameter , on an earlier result of Servedio (Comput Complex 16(2):180-209, 2007) which gave a bound. Our improvement is obtained via a new proof technique that uses strong anti-concentration bounds from probability theory. The new technique also gives a simple and modular proof of the original result of Servedio (Comput Complex 16(2):180-209, 2007) and extends to give low-weight approximators for threshold functions under a range of probability distributions other than the uniform distribution.
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