For regular expressions in (strong) star normal form a large set of efficient algorithms is known, from conversions into finite automata to characterisations of unambiguity. In this paper we study the average complexi...
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For regular expressions in (strong) star normal form a large set of efficient algorithms is known, from conversions into finite automata to characterisations of unambiguity. In this paper we study the average complexity of this class of expressions using analytic *** it is not always feasible to obtain explicit expressions for the generating functions involved, here we show how to get the required information for the asymptotic estimates with an indirect use of the existence of Puiseux expansions at singularities. We study, asymptotically and on average, the alphabetic size, the size of the epsilon-follow automaton and of the position automaton, as well as the ratio and the size of these expressions to standard regular expressions.
We consider uniform random permutations in classes having a finite combinatorial specification for the substitution decomposition. These classes include (but are not limited to) all permutation classes with a finite n...
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We consider uniform random permutations in classes having a finite combinatorial specification for the substitution decomposition. These classes include (but are not limited to) all permutation classes with a finite number of simple permutations. Our goal is to study their limiting behavior in the sense of permutons. The limit depends on the structure of the specification restricted to families with the largest growth rate. When it is strongly connected, two cases occur. If the associated system of equations is linear, the limiting permuton is a deterministic X-shape. Otherwise, the limiting permuton is the Brownian separable permuton, a random object that already appeared as the limit of most substitution-closed permutation classes, among which the separable permutations. Moreover these results can be combined to study some non strongly connected cases. To prove our result, we use a characterization of the convergence of random permutons by the convergence of random subpermutations. Key steps are the combinatorial study, via substitution trees, of families of permutations with marked elements inducing a given pattern, and the singularity analysis of the corresponding generating functions. (c) 2022 Elsevier Inc. All rights reserved.
Although regular expressions do not correspond univocally to regular languages, it is still worthwhile to study their properties and algorithms. For the average case analysis one often relies on the uniform random gen...
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Although regular expressions do not correspond univocally to regular languages, it is still worthwhile to study their properties and algorithms. For the average case analysis one often relies on the uniform random generation using a specific grammar for regular expressions, that can represent regular languages with more or less redundancy. Generators that are uniform on the set of expressions are not necessarily uniform on the set of regular languages. Nevertheless, it is not straightforward that asymptotic estimates obtained by considering the whole set of regular expressions are different from those obtained using a more refined set that avoids some large class of equivalent expressions. In this paper we study a set of expressions that avoid a given absorbing pattern. It is shown that, although this set is significantly smaller than the standard one, the asymptotic average estimates for the size of the Glushkov automaton for these expressions does not differ from the standard case. Furthermore, for this set the asymptotic density of epsilon-accepting expressions is also the same as for the set of all standard regular expressions.
A digital search tree (DST) - one of the most fundamental data structures on words - is a digital tree in which keys (strings, words) are stored directly in (internal) nodes. Such trees find myriad of applications fro...
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ISBN:
(纸本)9780898716740
A digital search tree (DST) - one of the most fundamental data structures on words - is a digital tree in which keys (strings, words) are stored directly in (internal) nodes. Such trees find myriad of applications from the popular Lempel- Ziv'78 data compression scheme to distributed hash tables. The profile of a DST measures the number of nodes at the same distance from the root; it is a function of the number of stored strings and the distance from the root. Most parameters of DST (e.g., height, fill-up) can be expressed in terms of the profile. However, from the inception of DST, the analysis of the profile has been elusive and it has become a prominent open problem in the area of analysis of algorithms. We make here the first, but decisive, step towards solving this problem. We present a precise analysis of the average profile when stored strings are generated by a biased memoryless source. The main technical difficulty of analyzing the profile lies in solving a sophisticated recurrence equation. We present such a solution for the Poissonized version of the problem (i.e., when the number of stored strings is generated by a Poisson distribution) in the Mellin transform domain. To accomplish it, we introduce a novel functional operator that allows us to express the solution in an explicit form, and then using analytic algorithmics tools to extract the asymptotic behavior of the profile. This analysis is surprisingly demanding but once it is carried out it reveals unusually intriguing and interesting behavior. The average profile undergoes several phase transitions when moving from the root to the longest path. At first, it resembles a full tree until it abruptly starts growing polynomially and it oscillates in this range. Our results are derived by methods of analytic algorithmics such as generating functions, Mellin transform, Poissonization and de-Poissonization, the saddle-point method, singularity analysis and uniform asymptotic analysis.
The Horton-Strahler number naturally arose from problems in various fields, e.g., geology, molecular biology and computer science. Consequently, detailed investigations of related parameters for different classes of b...
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The Horton-Strahler number naturally arose from problems in various fields, e.g., geology, molecular biology and computer science. Consequently, detailed investigations of related parameters for different classes of binary tree structures are of interest. This paper shows one possibility of how to perform a mathematical analysis for parameters related to the Horton-Strahler number in a unified way such that only a single analysis is needed to obtain results for many different classes of trees. The method is explained by the examples of the expected Horton-Strahler number and the related rth moments, the average number of critical nodes, and the expected distance between critical nodes. (C) 2002 Wiley Periodicals. Inc.
The JPDA filter for multiobject tracking assumes that the number of objects is given. The objects are assumed mutually independent, but different objects may have different state spaces. In this paper the objects are ...
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ISBN:
(纸本)9781509020126
The JPDA filter for multiobject tracking assumes that the number of objects is given. The objects are assumed mutually independent, but different objects may have different state spaces. In this paper the objects are extended, meaning that they can produce more than one sensor measurement, or highlight. Object highlights are modeled as a Poisson point process in the measurement space conditioned on the object's state. A new JPDA intensity filter (JiFi) is derived. It estimates an intensity function for each object, where the intensity is the expected number of highlights per unit object state space. A significant advantage of JiFi is that it avoids the extensive association probability calculations that are needed for JPDA. It is derived using an analytic combinatoric method based on probability generating functionals. Examples are given.
The Gödel–Dummett logic and Łukasiewicz one are two main many-valued logics used by the fuzzy logic community. Our goal is a quantitative comparison of these two. In this paper, we will mostly consider the 3-val...
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The Gödel–Dummett logic and Łukasiewicz one are two main many-valued logics used by the fuzzy logic community. Our goal is a quantitative comparison of these two. In this paper, we will mostly consider the 3-valued Gödel–Dummett logic as well as the 3-valued Łukasiewicz one. We shall concentrate on their implicational-negation fragments which are limited to formulas formed with a fixed finite number of variables. First, we investigate the proportion of the number of true formulas of a certain length n to the number of all formulas of such length built with exactly one variable. Then, we investigate such proportion for satisfiable formulas. Second, we generalise our investigation on formulas written with (Formula presented.) variables. The primary goal of the paper is the research on the asymptotic behaviour of these fractions when the length n tends to infinity. If such limits exists, they are real numbers between 0 and 1, which are called the density of truth or the density of SAT. To compare the density of truth and the density of satisfiable formulas for both fragments of 3-valued Gödel–Dummett's and Łukasiewicz's logics we use the powerful theory of analytic combinatorics. This paper is a natural continuation of the previous brief conference note by Kostrzycka and Zaionc (2020) as well as enriched with some previous results from Kostrzycka and Zaionc (2003). In the conference note we computed analytically the density of truth and the density of SAT (with a determined precision) for 3-valued Łukasiewicz's logic restricted to a language with only one variable. In Kostrzycka and Zaionc (2003) we computed the same values for exactly the same fragment of the 3-valued Gödel–Dummett logic. This paper answers the more general questions of the existence of density of truth and density of SAT for both many-valued logics with an arbitrary finite number of variables. Therefore this paper gives an an interesting picture of two main families of finite-valued fuzzy logics prob
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