46698746
GridSPiM: A Framework for Simple Locality and Containment in the Stochastic pi-Calculus
Process calculi hold great promise for modeling and analysis of cellular mechanics and behavior. While measured success has been achieved in their simulation of specific biochemical pathways and molecular mechanisms within the cell, several obstacles remain to their widespread adoption and use. Chiefly, these have to with the difficulty of modeling cell membranes and localized behavior, and limitations on the scalability of the execution model. This paper describes a multi-layered formalism --- GridSPiM --- that engages notions of concurrency, locality and encapsulation to provide a framework suitable for capturing the key aspects of cellular processes.
9161104
A Framework for High Assurance Security of Distributed Objects
High assurance security is difficult to achieve in distributed computer systems and databases because of their complexity, non-determinism and inherent heterogeneity. The practical application of formal methods is the key to high assurance security in open, distributed environments. This paper proposes the use of formal methods and a special layered architecture to achieve secure interoperation of heterogeneous distributed objects. The foundation is provided by ROC, a process calculus tailored for concurrent objects. Lying above ROC in the layered architecture is a meta-object model for creating object models with various programming constructs, mega-programming facilities and security mechanisms. Successive layers of the architecture represent more sophisticated toolkits for modeling distributed objects. Since each layer inherits ROC’s formal foundation, it automatically has an unambiguous semantics and supports verification.
753928
Policy mediation for multi-enterprise environments
Existing software infrastructures and middleware provide uniform security services across heterogeneous information networks. However few, if any, tools exist that support access control policy management for and between large enterprise information networks. Insiders often exploit gaps in policies to mount devastating attacks. This paper presents a Policy Machine and Policy Mediation Architecture for coordinating diverse policies in large information networks. The language-based approach adopted by each of these technologies permits local and global access control policy validation with static analysis and other formal techniques. Together the Policy Machine and Policy Mediation Architecture comprise an effective system for closing policy gaps in multi-enterprise environments.
20438390
Programmable Access Control
Software developers rely on sophisticated programming language protection models and APIs to manifest security policies for Internet applications. These tools do not provide suitable expressiveness for fine-grained, configurable policies. Nor do they ensure the consistency of a given policy implementation across objects in a heterogeneous environment. Programmable access control provides syntactic and semantic constructs in programming languages for systematically embedding security functionality within applications. Secure interoperability is of utmost importance in a distributed heterogeneous environment This paper introduces a methodology for programmable security by language extension, as well as a prototype model and implementation of JPAC, a programmable access control extension to Java. A coor-. dination language is also presented to support secure interoperability within the framework.
6476795
Content-based alternatives to conventional network monitoring systems
Network monitoring and management rely extensively upon network protocol identification as one of the most basic acts of analysis of network traffic. However, the conventional method of identifying network protocols based upon standard or well-known port numbers is no longer sufficient for modern networks, given the propensities for users and programs to change ports dynamically or use nonstandard ports. Unfortunately, this calls into question the ability of the collection of standard tools to gather reliable network intelligence.
16766690
Security policy coordination for heterogeneous information systems
Coordinating security policies in information enclaves is challenging due to their heterogeneity and autonomy. Administrators must reconcile the semantic diversity of data and security models before negotiating secure interoperation. This paper proposes an architecture that uses mediators and a primitive ticket-based authorization model to manage disparate policies in information enclaves. The formal foundation of the architecture facilitates static and dynamic analysis of global consistency and policy enforcement.
5490143
A Probabilistic Earley Parser as a Psycholinguistic Model
In human sentence processing, cognitive load can be defined many ways. This report considers a definition of cognitive load in terms of the total probability of structural options that have been disconfirmed at some point in a sentence: the surprisal of word wi given its prefix wo...i-1 on a phrase-structural language model. These loads can be efficiently calculated using a probabilistic Earley parser (Stolcke, 1995) which is interpreted as generating predictions about reading time on a word-by-word basis. Under grammatical assumptions supported by corpus-frequency data, the operation of Stolcke's probabilistic Earley parser correctly predicts processing phenomena associated with garden path structural ambiguity and with the subject/object relative asymmetry.
431369
The Information-Processing Difficulty Of Incremental Parsing
When an incremental parser gets the next word, its expectations about upcoming grammatical structures can change. When a word greatly constrains these grammatical expectations, uncertainty is reduced. This elimination of possibilities constitutes information processing work. Formalizing this notion of information processing work yields a complexity metric that predicts human repetition accuracy scores across a systematic class of linguistic phenomena, the Accessibility Hierarchy of relativizable grammatical relations.
5567072
Surprising Parser Actions and Reading Difficulty
An incremental dependency parser's probability model is entered as a predictor in a linear mixed-effects model of German readers' eye-fixation durations. This dependency-based predictor improves a baseline that takes into account word length, n-gram probability, and Cloze predictability that are typically applied in models of human reading. This improvement obtains even when the dependency parser explores a tiny fraction of its search space, as suggested by narrow-beam accounts of human sentence processing such as Garden Path theory.