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On the Structure of Inductive Reasoning: Circular and TreeShaped Proofs in the µCalculus
 IN PROCEEDINGS OF FOSSACS 2003
, 2003
"... In this paper we study induction in the context of the firstorder µcalculus with explicit approximations. We present and compare two Gentzenstyle proof systems each using a different type of induction. The first is ..."
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Cited by 20 (2 self)
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In this paper we study induction in the context of the firstorder µcalculus with explicit approximations. We present and compare two Gentzenstyle proof systems each using a different type of induction. The first is
A Fully Asynchronous Reader/Writer Mechanism for Multiprocessor RealTime Systems
, 1997
"... Data sharing among tasks within multiprocessor realtime systems is a crucial issue. This report presents a fully asynchronous mechanism of sharing data between a single writer and multiple readers. The writer and all the readers are allowed to access the shared data asynchronously in a loopfree an ..."
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Cited by 17 (1 self)
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Data sharing among tasks within multiprocessor realtime systems is a crucial issue. This report presents a fully asynchronous mechanism of sharing data between a single writer and multiple readers. The writer and all the readers are allowed to access the shared data asynchronously in a loopfree and waitfree manner because neither locking operations nor repeated actions of readandcheck are involved. Its implementation uses only (n + 2) buffer slots for n readers, and employs an atomic `StoreIfZero ' operation which can be easily simulated with the CompareandSwap instruction. Since neither writing nor reading the shared data imposes any effect upon other tasks in the system, this mechanism introduces no impact upon the timing behaviour of tasks. When employed by realtime applications, it helps to reduce blocking and priority inversion problems incurred by the commonly used lockbased synchronization mechanisms. 1 Introduction Data sharing is a basic approach to achieving inter...
Asynchronous Data Sharing in Multiprocessor RealTime Systems Using Process Consensus
 Proc. 10th Euromicro Workshop on RealTime Systems
, 1998
"... This report presents an approach to implementing fully asynchronous reader/writer mechanisms which addresses the problems of priority inversion and blocking among tasks within multiprocessor realtime systems. The approach is conceived from the concept of process consensus that the writer and the re ..."
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This report presents an approach to implementing fully asynchronous reader/writer mechanisms which addresses the problems of priority inversion and blocking among tasks within multiprocessor realtime systems. The approach is conceived from the concept of process consensus that the writer and the reader come to an agreement on accessing the shared data before proceeding to carry out their respective data operations. Because neither locking operations nor repeated actions of readandcheck are involved, the shared data can be accessed at any time by the writer and all the readers in a manner not only waitfree but also loopfree. In addition, data sharing through this approach introduces no impact upon either timing behaviour or schedulability of any task in the system. Hence the approach can help to remove priority inversion and blocking incurred by the commonly used lockbased synchronization mechanisms. 1 Introduction The implementation of shared data objects is a very important iss...
Complementing role models with Petri nets in studying asynchronous data communications
, 1998
"... . Simpson's role model method was designed for the analysis of synchronisationfree data communication mechanisms employing shared memory and has been shown to be especially useful for the representation and analyses of data freshness properties. Previously published analyses using the role mod ..."
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Cited by 5 (4 self)
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. Simpson's role model method was designed for the analysis of synchronisationfree data communication mechanisms employing shared memory and has been shown to be especially useful for the representation and analyses of data freshness properties. Previously published analyses using the role model method have employed proprietary state space search techniques developed by Simpson. In this paper, a formal definition of role models is given and a way of representing role models using Petri nets is presented. Potential advantages of analysing systems using the role model method complemented with Petri net techniques are demonstrated with a case study of data freshness properties of a data communication algorithm. Introduction The use of fully asynchronous processes is advantageous in many hard realtime distributed computer systems. For instance, the complete elimination of time interference in data communications between concurrent processes makes it possible to accurately predict the te...
Complementing The Role Model Method With Petri Net Techniques In Studying Issues Of Data Freshness Of The FourSlot Mechanism
, 1998
"... : Simpson's role model method [7, 8] was designed for the analysis of synchronisationfree data communication mechanisms employing shared memory and has been shown to be especially useful for the representation and analyses of data freshness properties. Previously published analyses using the r ..."
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Cited by 4 (1 self)
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: Simpson's role model method [7, 8] was designed for the analysis of synchronisationfree data communication mechanisms employing shared memory and has been shown to be especially useful for the representation and analyses of data freshness properties. Previously published analyses using the role model method have employed proprietary state space search techniques developed by Simpson. Here a formal definition of role models is given and a way of representing role models using Petri nets is presented. Potential advantages of analysing systems using the role model method complemented with Petri net techniques are demonstrated with a case study of data freshness properties of a data communication algorithm. 1. INTRODUCTION The use of fully asynchronous processes is advantageous in many hard realtime distributed computer systems. For instance, the complete elimination of time interference in data communications between concurrent processes makes it possible to accurately predict the t...
LIMIT COMPLEXITIES REVISITED
"... Abstract. The main goal of this paper is to put some known results in a common perspective and to simplify their proofs. We start with a simple proof of a result from [7] saying that lim supn C(xn) (here C(xn) is conditional (plain) Kolmogorov complexity of x when n is known) equals C 0′ (x), the ..."
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Abstract. The main goal of this paper is to put some known results in a common perspective and to simplify their proofs. We start with a simple proof of a result from [7] saying that lim supn C(xn) (here C(xn) is conditional (plain) Kolmogorov complexity of x when n is known) equals C 0′ (x), the plain Kolmogorov complexity with 0 ′oracle. Then we use the same argument to prove similar results for prefix complexity (and also improve results of [4] about limit frequencies), a priori probability on binary tree and measure of effectively open sets. As a byproduct, we get a criterion of 0 ′ MartinLöf randomness (called also 2randomness) proved in [3]: a sequence ω is 2random if and only if there exists c such that any prefix x of ω is a prefix of some string y such that C(y) � y  − c. (In 1960ies this property was suggested in [1] as one of possible randomness definitions; its equivalence to 2randomness was shown in [3] while proving another 2randomness criterion (see also [5]): ω is 2random if and only if C(x) � x  − c for some c and infinitely many prefixes x of ω. Finally, we show that lowbasis theorem can be used to get alternative proofs for these results and to improve the result about effectively open sets; this stronger version implies the 2randomness criterion mentioned in the previous sentence. 1. Plain complexity By C(x) we mean the plain complexity of a binary string x (the length of the shortest description of x when an optimal description method is fixed, see [2]; no requirements about prefixes). By C(xn) we mean conditional complexity of x when n is given [2]. Superscript 0 ′ in C0 ′ means that we consider the relativized (with oracle 0 ′ , the universal enumerable set) version of complexity.
TAME HARMONIC BUNDLES AND AN APPLICATION
, 2006
"... Key words and phrases. — Higgs bundle, harmonic bundle, KobayashiHitchin correspondence, HermitianEinstein metric, BogomolovGieseker inequality, flat bundle, variation of polarized Hodge structure, quasi projective variety. ..."
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Key words and phrases. — Higgs bundle, harmonic bundle, KobayashiHitchin correspondence, HermitianEinstein metric, BogomolovGieseker inequality, flat bundle, variation of polarized Hodge structure, quasi projective variety.