Naming and Identity in Epistemic Logics Part I: The Propositional Case

Abadi has introduced a logic to explicate the meaning of local names in SDSI, the Simple Distributed Security Infrastructure proposed by Rivest and Lampson. Abadi's logic does not correspond precisely to SDSI, however; it draws conclusions about local names that do not follow from SDSI's name resolution algorithm. Moreover, its semantics is somewhat unintuitive. This paper presents the Logic of Local Name Containment, which does not suffer from these deficiencies. It has a clear semantics and provides a tight characterization of SDSI name resolution. The semantics is shown to be closely related to that of logic programs, leading to an approach to the efficient implementation of queries concerning local names. A complete axiomatization of the logic is also provided.

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“…(We remark that Self is essentially the same as I in the logic of naming considered in [GH93].) Intuitively, Self denotes the current principal.…”

Section: Selfmentioning

confidence: 99%

A logic for SDSI's linked local name spaces

Halpern

Meyden

2001

JCS

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“…The intended interpretation of the first formula is just what we said above: "X is a T -prefix of my ledger"; the intended interpretation of the second formula is "I am honest". These are agent-relative formulas; following [3,4], we give such formulas semantics by having an agent on the left-hand side of |= as well as (I , r, m). We have to redefine the semantics of all formulas in the more general setting.…”

Section: ∆-2-common Knowledge and Indexical Setsmentioning

confidence: 99%

A Knowledge-Based Analysis of the Blockchain Protocol

Halpern

Pass

2017

Electron. Proc. Theor. Comput. Sci.

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At the heart of the Bitcoin is a blockchain protocol, a protocol for achieving consensus on a public ledger that records bitcoin transactions. To the extent that a blockchain protocol is used for applications such as contract signing and making certain transactions (such as house sales) public, we need to understand what guarantees the protocol gives us in terms of agents' knowledge. Here, we provide a complete characterization of agent's knowledge when running a blockchain protocol using a variant of common knowledge that takes into account the fact that agents can enter and leave the system, it is not known which agents are in fact following the protocol (some agents may want to deviate if they can gain by doing so), and the fact that the guarantees provided by blockchain protocols are probabilistic. We then consider some scenarios involving contracts and show that this level of knowledge suffices for some scenarios, but not others.

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“…Following Grove and Halpern [16,17] (GH from now on), we distinguish between agents and their names. We assume that programs mention only names, not agents (since in general the programmer will have access only to the names, which can be viewed as denoting roles).…”

Section: Standard Programs With Shared Namesmentioning

confidence: 99%

“…We deal with these problems by using techniques introduced by Moses and Roth [30] and further developed by Grove and Halpern [16,17]. Observe that it makes perfect sense to talk about each agent acting based on his own knowledge by saying "if I know ϕ, then …".…”

Section: Introductionmentioning

confidence: 99%

A knowledge-based analysis of global function computation

Halpern

Petride

2010

Distrib. Comput.

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Consider a distributed system N in which each agent has an input value and each communication link has a weight. Given a global function, that is, a function f whose value depends on the whole network, the goal is for every agent to eventually compute the value f (N ). We call this problem global function computation. Various solutions for instances of this problem, such as Boolean function computation, leader election, (minimum) spanning tree construction, and network determination, have been proposed, each under particular assumptions about what processors know about the system and how this knowledge can be acquired. We give a necessary and sufficient condition for the problem to be solvable that generalizes a number of well-known results (Attyia et al. in J ACM 35(4):845-875, 1988; Yamashita and Kameda in IEEE Trans Parallel Distrib Syst 7(1):69-89, 1996; Yamashita and Kameda in IEEE Trans Parallel Distrib Syst 10(9):878-887, 1999). We then provide a knowledge-based (kb) program (like those of Fagin et al. (Reasoning about knowledge, MIT Press,

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Naming and Identity in Epistemic Logics Part I: The Propositional Case

Cited by 36 publications

References 5 publications

A logic for SDSI's linked local name spaces

A logic for SDSI's linked local name spaces

A Knowledge-Based Analysis of the Blockchain Protocol

A knowledge-based analysis of global function computation

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