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OpenFst: A general and efficient weighted finitestate transducer library. Implementation and Application of Automata
, 2007
"... Abstract. We describe OpenFst, an opensource library for weighted finitestate transducers (WFSTs). OpenFst consists of a C++ template library with efficient WFST representations and over twentyfive operations for constructing, combining, optimizing, and searching them. At the shellcommand level, ..."
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Cited by 97 (11 self)
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Abstract. We describe OpenFst, an opensource library for weighted finitestate transducers (WFSTs). OpenFst consists of a C++ template library with efficient WFST representations and over twentyfive operations for constructing, combining, optimizing, and searching them. At the shellcommand level, there are corresponding transducer file representations and programs that operate on them. OpenFst is designed to be both very efficient in time and space and to scale to very large problems. This library has key applications speech, image, and natural language processing, pattern and string matching, and machine learning. We give an overview of the library, examples of its use, details of its design that allow customizing the labels, states, and weights and the lazy evaluation of many of its operations. Further information and a download of the OpenFst library can be obtained from
Theory and Algorithms for Modern Problems in Machine Learning and an Analysis of Markets
, 2008
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A Probabilistic Kleene Theorem
"... We provide a Kleene Theorem for (Rabin) probabilistic automata over finite words. Probabilistic automata generalize deterministic finite automata and assign to a word an acceptance probability. We provide probabilistic expressions with probabilistic choice, guarded choice, concatenation, and a sta ..."
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Cited by 2 (1 self)
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We provide a Kleene Theorem for (Rabin) probabilistic automata over finite words. Probabilistic automata generalize deterministic finite automata and assign to a word an acceptance probability. We provide probabilistic expressions with probabilistic choice, guarded choice, concatenation, and a star operator. We prove that probabilistic expressions and probabilistic automata are expressively equivalent. Our result actually extends to twoway probabilistic automata with pebbles and corresponding expressions.
Beyond Differential Privacy: Composition Theorems and Relational Logic for fdivergences between Probabilistic Programs
"... Abstract. fdivergences form a class of measures of distance between probability distributions; they are widely used in areas such as information theory and signal processing. In this paper, we unveil a new connection between fdivergences and differential privacy, a confidentiality policy that prov ..."
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Cited by 1 (0 self)
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Abstract. fdivergences form a class of measures of distance between probability distributions; they are widely used in areas such as information theory and signal processing. In this paper, we unveil a new connection between fdivergences and differential privacy, a confidentiality policy that provides strong privacy guarantees for private datamining; specifically, we observe that the notion of αdistance used to characterize approximate differential privacy is an instance of the family offdivergences. Building on this observation, we generalize to arbitrary fdivergences the sequential composition theorem of differential privacy. Then, we propose a relational program logic to prove upper bounds for the fdivergence between two probabilistic programs. Our results allow us to revisit the foundations of differential privacy under a new light, and to pave the way for applications that use different instances of fdivergences. 1
LOGICAL METHODS
"... Abstract. The value 1 problem is a decision problem for probabilistic automata over finite words: given a probabilistic automaton, are there words accepted with probability arbitrarily close to 1? This problem was proved undecidable recently; to overcome this, several classes of probabilistic automa ..."
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Abstract. The value 1 problem is a decision problem for probabilistic automata over finite words: given a probabilistic automaton, are there words accepted with probability arbitrarily close to 1? This problem was proved undecidable recently; to overcome this, several classes of probabilistic automata of different nature were proposed, for which the value 1 problem has been shown decidable. In this paper, we introduce yet another class of probabilistic automata, called leaktight automata, which strictly subsumes all classes of probabilistic automata whose value 1 problem is known to be decidable. We prove that for leaktight automata, the value 1 problem is decidable (in fact, PSPACEcomplete) by constructing a saturation algorithm based on the computation of a monoid abstracting the behaviours of the automaton. We rely on algebraic techniques developed by Simon to prove that this abstraction is complete. Furthermore, we adapt this saturation algorithm to decide whether an automaton is leaktight. Finally, we show a reduction allowing to extend our decidability results from finite words to infinite ones, implying that the value 1 problem for probabilistic leaktight parity automata is decidable.
Continuity Properties of Distances for Markov Processes (With Proof Appendix)
"... Abstract. In this paper we investigate distance functions on finite state Markov processes that measure the behavioural similarity of nonbisimilar processes. We consider both probabilistic bisimilarity metrics, and tracebased distances derived from standard Lp and KullbackLeibler distances. Two ..."
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Abstract. In this paper we investigate distance functions on finite state Markov processes that measure the behavioural similarity of nonbisimilar processes. We consider both probabilistic bisimilarity metrics, and tracebased distances derived from standard Lp and KullbackLeibler distances. Two desirable continuity properties for such distances are identified. We then establish a number of results that show that these two properties are in conflict, and not simultaneously fulfilled by any of our candidate natural distance functions. An impossibility result is derived that explains to some extent the fundamental difficulty we encounter. 1
c ○ World Scientific Publishing Company Lp Distance and Equivalence of Probabilistic Automata
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International Journal of Foundations of Computer Science c ○ World Scientific Publishing Company General Algorithms for Testing the Ambiguity of Finite Automata and the DoubleTape Ambiguity of FiniteState Transducers
"... We present efficient algorithms for testing the finite, polynomial, and exponential ambiguity of finite automata with ǫtransitions. We give an algorithm for testing the exponential ambiguity of an automaton A in time O(A  2 E), and finite or polynomial ambiguity in time O(A  3 E), where AE de ..."
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We present efficient algorithms for testing the finite, polynomial, and exponential ambiguity of finite automata with ǫtransitions. We give an algorithm for testing the exponential ambiguity of an automaton A in time O(A  2 E), and finite or polynomial ambiguity in time O(A  3 E), where AE denotes the number of transitions of A. These complexities significantly improve over the previous best complexities given for the same problem. Furthermore, the algorithms presented are simple and based on a general algorithm for the composition or intersection of automata. Additionally, we give an algorithm to determine in time O(A  3 E) the degree of polynomial ambiguity of a polynomially ambiguous automaton A and present an application of our algorithms to an approximate computation of the entropy of a probabilistic automaton. We also study the doubletape ambiguity of finitestate transducers. We show that the general problem is undecidable and that it is NPhard for acyclic transducers. We present a specific analysis of the doubletape ambiguity of transducers with bounded delay. In particular, we give a characterization of doubletape ambiguity for synchronized transducers with zero delay that can be tested in quadratic time and give an algorithm for testing the doubletape ambiguity of transducers with bounded delay.