64 research outputs found
A Secure PLAN (Extended Version)
Active networks promise greater flexibility than current networks, but threaten safety and security by virtue of their programmability. We describe the design and implementation of a security architecture for the active network PLANet (Hicks et al., 1999). Security is obtained with a two-level architecture that combines a functionally restricted packet language, PLAN (Hicks et al., 1998), with an environment of general-purpose service routines governed by trust management (Blaze et al., 1996). In particular, we employ a technique which expands or contracts a packet's service environment based on its level of privilege, termed namespace-based security. As an application of our security architecture, we present the design and implementation of an active-network firewall. We find that the addition of the firewall imposes an approximately 34% latency overhead and as little as a 6.7% space overhead to incoming packets
A Logic Programming Approach to Knowledge-State Planning: Semantics and Complexity
We propose a new declarative planning language, called K, which is based on
principles and methods of logic programming. In this language, transitions
between states of knowledge can be described, rather than transitions between
completely described states of the world, which makes the language well-suited
for planning under incomplete knowledge. Furthermore, it enables the use of
default principles in the planning process by supporting negation as failure.
Nonetheless, K also supports the representation of transitions between states
of the world (i.e., states of complete knowledge) as a special case, which
shows that the language is very flexible. As we demonstrate on particular
examples, the use of knowledge states may allow for a natural and compact
problem representation. We then provide a thorough analysis of the
computational complexity of K, and consider different planning problems,
including standard planning and secure planning (also known as conformant
planning) problems. We show that these problems have different complexities
under various restrictions, ranging from NP to NEXPTIME in the propositional
case. Our results form the theoretical basis for the DLV^K system, which
implements the language K on top of the DLV logic programming system.Comment: 48 pages, appeared as a Technical Report at KBS of the Vienna
University of Technology, see http://www.kr.tuwien.ac.at/research/reports
Answer Set Planning Under Action Costs
Recently, planning based on answer set programming has been proposed as an
approach towards realizing declarative planning systems. In this paper, we
present the language Kc, which extends the declarative planning language K by
action costs. Kc provides the notion of admissible and optimal plans, which are
plans whose overall action costs are within a given limit resp. minimum over
all plans (i.e., cheapest plans). As we demonstrate, this novel language allows
for expressing some nontrivial planning tasks in a declarative way.
Furthermore, it can be utilized for representing planning problems under other
optimality criteria, such as computing ``shortest'' plans (with the least
number of steps), and refinement combinations of cheapest and fastest plans. We
study complexity aspects of the language Kc and provide a transformation to
logic programs, such that planning problems are solved via answer set
programming. Furthermore, we report experimental results on selected problems.
Our experience is encouraging that answer set planning may be a valuable
approach to expressive planning systems in which intricate planning problems
can be naturally specified and solved
Roots and Effects of Investments' Misperception
This work deals with the problem of investors' irrational behavior and financial products' misperception. The theoretical analysis of the mechanisms driving wrong evaluations of investment performances is explored. The study is supported by the application of Monte Carlo simulations to the remarkable case of structured financial products. Some motivations explaining the popularity among retail investors of these complex financial instruments are also provided. Investors are assumed to compare the performances of different projects through stochastic dominance rules and, to pursue our scopes, a new definition of this decision criteria is introduced.
Social and emotional aspects of learning (SEAL) programme in secondary schools : national evaluation
Agents in Network Management
The ubiquity and complexity of modern networks require automated management and control. With increases in scale, automated solutions based on simple data access models such as SNMP will give way to more distributed and algorithmic techniques. This article outlines present and near-term solutions based on the ideas of active networks and mobile agents, which permit sophisticated programmable control and management of ultra large scale networks
Scalable Resource Control in Active Networks
The increased complexity of the service model relative to store-and-forward routers has made resource management one of the paramount concerns in active networking research and engineering. In this paper,we address two major challenges in scaling resource management-to-many-node active networks. The first is the use of market mechanisms and trading amongst nodes and programs with varying degrees of competition and cooperation to provide a scalable approach to managing active network resources. The second is the use of a trust-management architecture to ensure that the participants in the resource management marketplace have a policy-driven "rule of law" in which marketplace decisions can be made and relied upon. We have used lottery scheduling and the Keynote trust-management system for our implementation, for which we provide some initial performance indications
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