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104
Datalog with Constraints: A Foundation for Trust Management Languages
 In PADL ’03: Proceedings of the 5th International Symposium on Practical Aspects of Declarative Languages
, 2003
"... Trust management (TM) is a promising approach for authorization and access control in distributed systems, based on signed distributed policy statements expressed in a policy language. Although several TM languages are semantically equivalent to subsets of Datalog, Datalog is not su#ciently expr ..."
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Cited by 94 (11 self)
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Trust management (TM) is a promising approach for authorization and access control in distributed systems, based on signed distributed policy statements expressed in a policy language. Although several TM languages are semantically equivalent to subsets of Datalog, Datalog is not su#ciently expressive for finegrained control of structured resources. We define the class of linearly decomposable unary constraint domains, prove that Datalog extended with constraints in any combination of such constraint domains is tractable, and show that permissions associated with structured resources fall into this class. We also present a concrete declarative TM language, RT 1 , based on constraint Datalog, and use constraint Datalog to analyze another TM system, KeyNote, which turns out to be less expressive than RT 1 in significant respects, yet less tractable in the worst case. Although constraint Datalog has been studied in the context of constraint databases, TM applications involve di#erent kinds of constraint domains and have different computational complexity requirements.
Generating Finite State Machines from Abstract State Machines
 in Proceedings of International Symposium on Software Testing and Analysis (ISSTA
, 2002
"... We give an algorithm that derives a finite state machine (FSM) from a given abstract state machine (ASM) specification. This allows us to integrate ASM specs with the existing tools for test case generation from FSMs. ASM specs are executable but have typically too many, often infinitely many states ..."
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Cited by 68 (21 self)
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We give an algorithm that derives a finite state machine (FSM) from a given abstract state machine (ASM) specification. This allows us to integrate ASM specs with the existing tools for test case generation from FSMs. ASM specs are executable but have typically too many, often infinitely many states. We group ASM states into finitely many hyperstates which are the nodes of the FSM. The links of the FSM are induced by the ASM state transitions.
Quantum Algorithm For Hilberts Tenth Problem
 Int.J.Theor.Phys
, 2003
"... We explore in the framework of Quantum Computation the notion of Computability, which holds a central position in Mathematics and Theoretical Computer Science. A quantum algorithm for Hilbert’s tenth problem, which is equivalent to the Turing halting problem and is known to be mathematically noncomp ..."
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Cited by 59 (10 self)
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We explore in the framework of Quantum Computation the notion of Computability, which holds a central position in Mathematics and Theoretical Computer Science. A quantum algorithm for Hilbert’s tenth problem, which is equivalent to the Turing halting problem and is known to be mathematically noncomputable, is proposed where quantum continuous variables and quantum adiabatic evolution are employed. If this algorithm could be physically implemented, as much as it is valid in principle—that is, if certain hamiltonian and its ground state can be physically constructed according to the proposal—quantum computability would surpass classical computability as delimited by the ChurchTuring thesis. It is thus argued that computability, and with it the limits of Mathematics, ought to be determined not solely by Mathematics itself but also by Physical Principles. 1
The Unknowable
, 1999
"... In the early twentieth century two extremely influential research programs aimed to establish solid foundations for mathematics with the help of new formal logic. The logicism of Gottlob Frege and Bertrand Russell claimed that all mathematics can be shown to be reducible to logic. David Hilbert and ..."
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Cited by 41 (2 self)
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In the early twentieth century two extremely influential research programs aimed to establish solid foundations for mathematics with the help of new formal logic. The logicism of Gottlob Frege and Bertrand Russell claimed that all mathematics can be shown to be reducible to logic. David Hilbert and his school in turn intended to demonstrate, using logical formalization, that the use of infinistic, settheoretical methods in mathematics—viewed with suspicion by many—can never lead to finitistically meaningful but false statements and is thus safe. This came to be known as Hilbert’s program. These grand aims were shown to be impossible by applying the exact methods of logic to itself: the limitative results of Kurt Gödel, Alonzo Church, and Alan Turing in the 1930s revolutionized the whole understanding of logic and mathematics (the key papers are reprinted in [5]). Panu Raatikainen is a fellow in the Helsinki Collegium for Advanced Study and a docent of theoretical philosophy at the University of Helsinki. His email address is
Computing over the reals: Foundations for scientific computing
 Notices of the AMS
"... We give a detailed treatment of the “bitmodel ” of computability and complexity of real functions and subsets of R n, and argue that this is a good way to formalize many problems of scientific computation. In Section 1 we also discuss the alternative BlumShubSmale model. In the final section we d ..."
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Cited by 32 (3 self)
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We give a detailed treatment of the “bitmodel ” of computability and complexity of real functions and subsets of R n, and argue that this is a good way to formalize many problems of scientific computation. In Section 1 we also discuss the alternative BlumShubSmale model. In the final section we discuss the issue of whether physical systems could defeat the ChurchTuring Thesis. 1
Computing the noncomputable
 Contemporary Physics
"... We explore in the framework of Quantum Computation the notion of computability, which holds a central position in Mathematics and Theoretical Computer Science. A quantum algorithm that exploits the quantum adiabatic which is equivalent to the Turing halting problem and known to be mathematically non ..."
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Cited by 30 (7 self)
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We explore in the framework of Quantum Computation the notion of computability, which holds a central position in Mathematics and Theoretical Computer Science. A quantum algorithm that exploits the quantum adiabatic which is equivalent to the Turing halting problem and known to be mathematically noncomputable. Generalised quantum algorithms are also considered for some other mathematical noncomputables in the same and of different noncomputability classes. The key element of all these algorithms is the measurability of both the values of physical observables and of the quantummechanical probability distributions for these values. It is argued that computability, and thus the limits of Mathematics, ought to be determined not
Calysto: Scalable and Precise Extended Static Checking
 ICSE 2008
, 2008
"... Automatically detecting bugs in programs has been a longheld goal in software engineering. Many techniques exist, tradingoff varying levels of automation, thoroughness of coverage of program behavior, precision of analysis, and scalability to large code bases. This paper presents the CALYSTO stati ..."
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Cited by 29 (3 self)
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Automatically detecting bugs in programs has been a longheld goal in software engineering. Many techniques exist, tradingoff varying levels of automation, thoroughness of coverage of program behavior, precision of analysis, and scalability to large code bases. This paper presents the CALYSTO static checker, which achieves an unprecedented combination of precision and scalability in a completely automatic extended static checker. CALYSTO is interprocedurally pathsensitive, fully contextsensitive, and bitaccurate in modeling data operations — comparable coverage and precision to very expensive formal analyses — yet scales comparably to the leading, less precise, staticanalysisbased tool for similar properties. Using CALYSTO, we have discovered dozens of bugs, completely automatically, in hundreds of thousands of lines of production, opensource applications, with a very low rate of false error reports. This paper presents the design decisions, algorithms, and optimizations behind CALYSTO’s performance.
An analysis framework for security in Web applications
 In Proceedings of the FSE Workshop on Specification and Verification of ComponentBased Systems (SAVCBS 2004
, 2004
"... ..."
Noncomputable Julia sets
 Journ. Amer. Math. Soc
"... Polynomial Julia sets have emerged as the most studied examples of fractal sets generated by a dynamical system. Apart from the beautiful mathematics, one of the reasons for their popularity is the beauty of the computergenerated images of such sets. The algorithms used to draw these pictures vary; ..."
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Cited by 26 (6 self)
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Polynomial Julia sets have emerged as the most studied examples of fractal sets generated by a dynamical system. Apart from the beautiful mathematics, one of the reasons for their popularity is the beauty of the computergenerated images of such sets. The algorithms used to draw these pictures vary; the most naïve work by iterating the center of a pixel to determine if it lies in the Julia set. Milnor’s distanceestimator algorithm [Mil] uses classical complex analysis to give a onepixel estimate of the Julia set. This algorithm and its modifications work quite well for many examples, but it is well known that in some particular cases computation time will grow very rapidly with increase of the resolution. Moreover, there are examples, even in the family of quadratic polynomials, when no satisfactory pictures of the Julia set exist. In this paper we study computability properties of Julia sets of quadratic polynomials. Under the definition we use, a set is computable, if, roughly speaking, its image can be generated by a computer with an arbitrary precision. Under this notion of computability we show: Main Theorem. There exists a parameter value c ∈ C such that the Julia set of
The Computational Complexity of Some Problems of Linear Algebra
 STACS '97
, 1997
"... We consider the computational complexity of some problems dealing with matrix rank. Let E; S be subsets of a commutative ring R. Let x 1 ; x 2 ; : : : ; x t be variables. Given a matrix M = M(x 1 ; x 2 ; : : : ; x t ) with entries chosen from E [ fx 1 ; x 2 ; : : : ; x t g, we want to determine ..."
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Cited by 23 (2 self)
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We consider the computational complexity of some problems dealing with matrix rank. Let E; S be subsets of a commutative ring R. Let x 1 ; x 2 ; : : : ; x t be variables. Given a matrix M = M(x 1 ; x 2 ; : : : ; x t ) with entries chosen from E [ fx 1 ; x 2 ; : : : ; x t g, we want to determine maxrank S (M) = max (a 1 ;a 2 ;:::;a t )2S t rank M(a 1 ; a 2 ; : : : a t ) and minrank S (M) = min (a 1 ;a 2 ;:::;a t )2S t rank M(a 1 ; a 2 ; : : : a t ): There are also variants of these problems that specify more about the structure of M , or instead of asking for the minimum or maximum