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Mimicry Attacks on HostBased Intrusion Detection Systems
 In Proceedings of the 9th ACM Conference on Computer and Communications Security
, 2002
"... ..."
Behavior Protocols for Software Components
 IEEE Transactions on Software Engineering
, 2002
"... In this paper, we propose a means to enhance an architecture description language with a description of component behavior. A notation used for this purpose should be able to express the "interplay" on the component's interfaces and reflect stepbystep refinement of the component's specification ..."
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Cited by 166 (32 self)
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In this paper, we propose a means to enhance an architecture description language with a description of component behavior. A notation used for this purpose should be able to express the "interplay" on the component's interfaces and reflect stepbystep refinement of the component's specification during its design. In addition, the notation should be easy to comprehend and allow for formal reasoning about the correctness of the specification refinement and also about the correctness of an implementation in terms of whether it adheres to the specification. Targeting all these requirements together, the paper proposes to employ behaviorprotocols which are based on a notation similar to regular expressions.
On The Computational Power Of Neural Nets
 JOURNAL OF COMPUTER AND SYSTEM SCIENCES
, 1995
"... This paper deals with finite size networks which consist of interconnections of synchronously evolving processors. Each processor updates its state by applying a "sigmoidal" function to a linear combination of the previous states of all units. We prove that one may simulate all Turing Machines by su ..."
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Cited by 159 (26 self)
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This paper deals with finite size networks which consist of interconnections of synchronously evolving processors. Each processor updates its state by applying a "sigmoidal" function to a linear combination of the previous states of all units. We prove that one may simulate all Turing Machines by such nets. In particular, one can simulate any multistack Turing Machine in real time, and there is a net made up of 886 processors which computes a universal partialrecursive function. Products (high order nets) are not required, contrary to what had been stated in the literature. Nondeterministic Turing Machines can be simulated by nondeterministic rational nets, also in real time. The simulation result has many consequences regarding the decidability, or more generally the complexity, of questions about recursive nets.
Precise analysis of string expressions
 In Proc. 10th International Static Analysis Symposium, SAS ’03, volume 2694 of LNCS
, 2003
"... We perform static analysis of Java programs to answer a simple question: which values may occur as results of string expressions? The answers are summarized for each expression by a regular language that is guaranteed to contain all possible values. We present several applications of this analysis, ..."
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Cited by 159 (15 self)
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We perform static analysis of Java programs to answer a simple question: which values may occur as results of string expressions? The answers are summarized for each expression by a regular language that is guaranteed to contain all possible values. We present several applications of this analysis, including statically checking the syntax of dynamically generated expressions, such as SQL queries. Our analysis constructs flow graphs from class files and generates a contextfree grammar with a nonterminal for each string expression. The language of this grammar is then widened into a regular language through a variant of an algorithm previously used for speech recognition. The collection of resulting regular languages is compactly represented as a special kind of multilevel automaton from which individual answers may be extracted. If a program error is detected, examples of invalid strings are automatically produced. We present extensive benchmarks demonstrating that the analysis is e#cient and produces results of useful precision.
Weighted finitestate transducers in speech recognition
 COMPUTER SPEECH & LANGUAGE
, 2002
"... We survey the use of weighted finitestate transducers (WFSTs) in speech recognition. We show that WFSTs provide a common and natural representation for hidden Markov models (HMMs), contextdependency, pronunciation dictionaries, grammars, and alternative recognition outputs. Furthermore, general tr ..."
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Cited by 147 (4 self)
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We survey the use of weighted finitestate transducers (WFSTs) in speech recognition. We show that WFSTs provide a common and natural representation for hidden Markov models (HMMs), contextdependency, pronunciation dictionaries, grammars, and alternative recognition outputs. Furthermore, general transducer operations combine these representations flexibly and efficiently. Weighted determinization and minimization algorithms optimize their time and space requirements, and a weight pushing algorithm distributes the weights along the paths of a weighted transducer optimally for speech recognition. As an example, we describe a North American Business News (NAB) recognition system built using these techniques that combines the HMMs, full crossword triphones, a lexicon of 40 000 words, and a large trigram grammar into a single weighted transducer that is only somewhat larger than the trigram word grammar and that runs NAB in realtime on a very simple decoder. In another example, we show that the same techniques can be used to optimize lattices for secondpass recognition. In a third example, we show how general automata operations can be used to assemble lattices from different recognizers to improve recognition performance.
Regular Path Queries with Constraints
 SYMPOSIUM ON PRINCIPLES OF DATABASE SYSTEMS
, 1997
"... The evaluation of path expression queries on semistructured data in a distributed asynchronous environment is considered. The focus is on the use of local information expressed in the form of path constraints in the optimization of path expression queries. In particular, decidability and complexity ..."
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Cited by 147 (6 self)
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The evaluation of path expression queries on semistructured data in a distributed asynchronous environment is considered. The focus is on the use of local information expressed in the form of path constraints in the optimization of path expression queries. In particular, decidability and complexity results on the implication problem for path constraints are established.
Fast Regular Expression Matching using FPGAs
, 2001
"... This paper presents an efficient method for finding matches to a given regular expression in given text using FPGAs. To match a regular expression of length n, a serial machine requires O(2 ) memory and takes O(1) time per text character. The proposed approach requires only O(n 2) space and still pr ..."
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Cited by 144 (15 self)
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This paper presents an efficient method for finding matches to a given regular expression in given text using FPGAs. To match a regular expression of length n, a serial machine requires O(2 ) memory and takes O(1) time per text character. The proposed approach requires only O(n 2) space and still processes a text character in O(1) time (one clock cycle). The improvement is due to the Nondeterministic Finite Automaton (NFA) used to perform the matching. As far as the authors are aware, this is the fnst practical use of a nondeterministic state machine on programmable logic.
Conversation specification: a new approach to design and analysis of eservice composition
 In World Wide Web Conference
, 2003
"... This paper introduces a framework for modeling and specifying the global behavior of eservice compositions. Under this framework, peers (individual eservices) communicate through asynchronous messages and each peer maintains a queue for incoming messages. A global “watcher ” keeps track of message ..."
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Cited by 142 (28 self)
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This paper introduces a framework for modeling and specifying the global behavior of eservice compositions. Under this framework, peers (individual eservices) communicate through asynchronous messages and each peer maintains a queue for incoming messages. A global “watcher ” keeps track of messages as they occur. We propose and study a central notion of a “conversation”, which is a sequence of (classes of) messages observed by the watcher. We consider the case where the peers are represented by Mealy machines (finite state machines with input and output). The sets of conversations exhibit unexpected behaviors. For example, there exists a composite eservice based on Mealy peers whose set of conversations is not context free (and not regular). (The set of conversations is always context sensitive.) One cause for this is the queuing of messages; we introduce an operator “prepone ” that simulates queue
Undecidability of Static Analysis
 ACM Letters on Programming Languages and Systems
, 1992
"... Static Analysis of programs is indispensable to any software tool, environment, or system that requires compile time information about the semantics of programs. With the emergence of languages like C and LISP, Static Analysis of programs with dynamic storage and recursive data structures has bec ..."
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Cited by 142 (5 self)
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Static Analysis of programs is indispensable to any software tool, environment, or system that requires compile time information about the semantics of programs. With the emergence of languages like C and LISP, Static Analysis of programs with dynamic storage and recursive data structures has become a field of active research. Such analysis is difficult, and the Static Analysis community has recognized the need for simplifying assumptions and approximate solutions. However, even under the common simplifying assumptions, such analyses are harder than previously recognized. Two fundamental Static Analysis problems are May Alias and Must Alias. The former is not recursive (i.e., is undecidable) and the latter is not recursively enumerable (i.e., is uncomputable), even when all paths are executable in the program being analyzed for languages with ifstatements, loops, dynamic storage, and recursive data structures. Categories and Subject Descriptors: D.3.1 [Programming Languages...