scispace - formally typeset
Search or ask a question
Book ChapterDOI

Highly Undecidable Questions for Process Algebras

11 Apr 2004-BRICS Report Series (Kluwer)-Vol. 11, Iss: 8, pp 507-520
TL;DR: This work shows Sigma^1_1-completeness of weak bisimilarity for PA (process algebra), and of weak simulation preorder/equivalence for PDA (pushdown automata), PA and PN (Petri nets).
Abstract: We show Sigma^1_1-completeness of weak bisimilarity for PA (process algebra), and of weak simulation preorder/equivalence for PDA (pushdown automata), PA and PN (Petri nets). We also show Pi^1_1-hardness of weak omega-trace equivalence for the (sub)classes BPA (basic process algebra) and BPP (basic parallel processes).

Content maybe subject to copyright    Report

Citations
More filters
Book ChapterDOI
15 Aug 2004
TL;DR: The concept of zero-knowledge (ZK) has become of fundamental importance in cryptography as mentioned in this paper, and it has become one of the most important concepts in cryptography in the quantum setting.
Abstract: The concept of zero-knowledge (ZK) has become of fundamental importance in cryptography. However, in a setting where entities are modeled by quantum computers, classical arguments for proving ZK fail to hold since, in the quantum setting, the concept of rewinding is not generally applicable. Moreover, known classical techniques that avoid rewinding have various shortcomings in the quantum setting.

70 citations

Journal ArticleDOI
TL;DR: A selection of recently developed and/or used techniques for equivalence-checking on infinite-state systems can be found in this article, with an up-to-date overview of existing results.
Abstract: The paper presents a selection of recently developed and/or used techniques for equivalence-checking on infinite-state systems, and an up-to-date overview of existing results (as of September 2004).

60 citations

Journal Article
TL;DR: A key result of this paper is a representation theorem showing how continuous valuations on the domain of a confusion-free event structure correspond to the probabilistic event structures it supports.
Abstract: This paper studies how to adjoin probability to event structures, leading to the model of probabilistic event structures. In their simplest form probabilistic choice is localised to cells, where conflict arises; in which case probabilistic independence coincides with causal independence. An application to the semantics of a probabilistic CCS is sketched. An event structure is associated with a domain-that of its configurations ordered by inclusion. In domain theory probabilistic processes are denoted by continuous valuations on a domain. A key result of this paper is a representation theorem showing how continuous valuations on the domain of a confusion-free event structure correspond to the probabilistic event structures it supports. We explore how to extend probability to event structures which are not confusion-free via two notions of probabilistic runs of a general event structure. Finally, we show how probabilistic correlation and probabilistic event structures with confusion can arise from event structures which are originally confusion-free by using morphisms to rename and hide events.

42 citations

Book ChapterDOI
15 Sep 2002
TL;DR: In this paper, the call graph of the source program is partitioned into strongly connected components, based on the simple observation that all functions in each component need the same extra parameters and thus a transitive closure is not needed.
Abstract: Lambda-lifting is a program transformation used in compilers and in partial evaluators and that operates in cubic time. In this article, we show how to reduce this complexity to quadratic time.Lambda-lifting transforms a block-structured program into a set of recursive equations, one for each local function in the source program. Each equation carries extra parameters to account for the free variables of the corresponding local function and of all its callees. It is the search for these extra parameters that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by a transitive closure.Instead, we partition the call graph of the source program into strongly connected components, based on the simple observation that all functions in each component need the same extra parameters and thus a transitive closure is not needed. We therefore simplify the search for extra parameters by treating each strongly connected component instead of each function as a unit, thereby reducing the time complexity of lambda-lifting from O(n3 log n) to O(n2 log n), where n is the size of the program.Since a lambda-lifter can output programs of size O(n2), we believe that our algorithm is close to optimal.

36 citations

Proceedings ArticleDOI
06 Jun 2005
TL;DR: The proof-carrying-request model is different than the notion of proof-of-compliance from traditional trust-management; in particular, all proofs are efficiently verifiable or easily rejected, but, in the worst case, may require as much communication as computing the actual trust-state itself.
Abstract: We consider distributed algorithms for solving a range of problems in a framework for trust in large-scale distributed systems. The framework is based on the notion of trust structures; a set of 'trust-levels' with two distinct partial orderings. In the trust model, a global trust-state is defined as the least fixed-point of a collection of local policies of nodes in the network. We show that it is possible to compute the global trust-state using a simple, robust and totally asynchronous distributed-algorithm. We also consider a distributed notion of proof-carrying-requests as a means of approximating the least fixed-point, enabling sound reasoning about the global trust-state without computing the exact fixed-point. Our proof-carrying-request model is different than the notion of proof-of-compliance from traditional trust-management; in particular, all proofs are efficiently verifiable or easily rejected, but, in the worst case, may require as much communication as computing the actual trust-state itself

33 citations

References
More filters
Journal ArticleDOI
TL;DR: Central concerns of the book are related theories of recursively enumerable sets, of degree of un-solvability and turing degrees in particular and generalizations of recursion theory.

3,665 citations

Book
22 Apr 1987
TL;DR: In this paper, the authors discuss related theories of recursively enumerable sets, degree of un-solvability and turing degrees in particular, and generalizations of recursion theory.
Abstract: Central concerns of the book are related theories of recursively enumerable sets, of degree of un-solvability and turing degrees in particular. A second group of topics has to do with generalizations of recursion theory. The third topics group mentioned is subrecursive computability and subrecursive hierarchies

1,779 citations

Journal ArticleDOI
TL;DR: If searching for the ebook by Hartley Rogers Theory of Recursive Functions and Effective Computability in pdf format, then you've come to the faithful site, which presented the complete version of this book in PDF, DjVu, doc, ePub, txt forms.
Abstract: If searching for the ebook by Hartley Rogers Theory of Recursive Functions and Effective Computability in pdf format, then you've come to the faithful site. We presented the complete version of this book in PDF, DjVu, doc, ePub, txt forms. You may reading Theory of Recursive Functions and Effective Computability online or download. As well as, on our site you can read guides and different artistic eBooks online, either downloading their as well. We like invite your note that our site does not store the book itself, but we give link to site whereat you can downloading either reading online. So if you have necessity to downloading pdf by Hartley Rogers Theory of Recursive Functions and Effective Computability , in that case you come on to the right site. We own Theory of Recursive Functions and Effective Computability PDF, doc, txt, DjVu, ePub formats. We will be happy if you return to us more.

1,124 citations


"Highly Undecidable Questions for Pr..." refers background in this paper

  • ...We also show Π11 - hardness of weak ω-trace equivalence for the (sub)classes BPA (basic process algebra) and BPP (basic parallel processes)....

    [...]

Book
01 Jan 1981
TL;DR: Algorithms, complexity analysis, and algorithmic ideas are introduced informally in Chapter 1, and are pursued throughout the book, each section is followed by problems.
Abstract: From the Publisher: Lewis and Papadimitriou present this long awaited Second Edition of their best-selling theory of computation. The authors are well-known for their clear presentation that makes the material accessible to a a broad audience and requires no special previous mathematical experience. In this new edition, the authors incorporate a somewhat more informal, friendly writing style to present both classical and contemporary theories of computation. Algorithms, complexity analysis, and algorithmic ideas are introduced informally in Chapter 1, and are pursued throughout the book. Each section is followed by problems.

1,093 citations

Book ChapterDOI
23 Aug 1993
TL;DR: In this paper, semantic equivalences and preorders for sequential systems with silent moves are studied, focusing on the ones that abstract from successful termination, stochastic and real-time aspects of the investigated systems, and the structure of the visible actions systems can perform.
Abstract: This paper studies semantic equivalences and preorders for sequential systems with silent moves, restricting attention to the ones that abstract from successful termination, stochastic and real-time aspects of the investigated systems, and the structure of the visible actions systems can perform. It provides a parameterized definition of such a preorder, such that most such preorders and equivalences found in the literature are obtained by a suitable instantiation of the parameters. Other instantiations yield preorders that combine properties from various semantics. Moreover, the approach shows several ways in which preorders that were originally only considered for systems without silent moves, most notably the ready simulation, can be generalized to an abstract setting, and how preorders that were originally only considered for for systems without divergence, such as the coupled simulation, can be extended to divergent systems. All preorders come with—or rather as—a modal characterization, and when possible also a relational characterization. The paper concludes with some pros and cons of the preorders.

878 citations