Petros S. Stefaneas

Theory, Practice, and Applications of Rules on the Web

We present textual logic (TL), a novel approach that enables rapid semi-automatic acquisition of rich logical knowledge from text. The resulting axioms are expressed as defeasible higher-order logic formulas in Rulelog, a novel extended form of declarative logic programs. A key element of TL is textual terminology, a phrasal style of knowledge in which words/word-senses are used directly as logical constants. Another key element of TL is a method for rapid interactive disambiguation as part of logic-based text interpretation. Existential quantifiers are frequently required, and we describe Rulelog’s approach to making existential knowledge be defeasible. We describe results from a pilot experiment that represented the knowledge from several thousand English sentences in the domain of college-level cell biology, for purposes of question-answering.

Formal analysis of TESLA protocol in the timed OTS/CafeOBJ method

The Timed Observational Transition System (TOTS)/CafeOBJ method is a version of the OTS/CafeOBJ method for modeling, specification and verification of distributed systems and protocols with real time constraints. In this paper we report on a case study from the field of source authentication protocols, TESLA protocol, to show the application of the method to such complex systems. We prove that our model of the protocol satisfies that the receiver does not accept as authentic any message unless it was actually sent by the sender. To verify the property we have used several other invariants which include timing information. To our knowledge, this is the first time that the method has been applied to the formal analysis of such a complex protocol.

Algebraic Specifications for OMA REL Licenses

OMA-Digital Rights Management System is a standard proposed by Open Mobile Alliance for protecting digital content distributed through mobile networks. In such a system, licenses are written in an appropriate language and used to ensure the fine grained consumption of contents. We claim that the Rights Expression Language (OMA-REL) does not rely on formal semantics. To address this problem we propose an abstract syntax for OMA-REL and write an algebraic specification of it using CafeOBJ, an executable algebraic specification language, with the future goal the creation of automated tools that check the behavior of a set of licenses under a certain environment.

Strategies for accelerating the worldwide adoption of e-commerce

In recent years, many organizations have recognized the potential of e-commerce to improve profitability by increasing productivity and market penetration while reducing costs. But the vision of an electronically interconnected world requires the global adoption of e-commerce, not just in industrialized nations, but also in developing ones, where most of worlds population lives. To successfully encourage the embrace of the Internet and e-commerce, one must carefully study the unique socioeconomic and cultural aspects of such nations. This article discusses ways to stimulate the worldwide adoption of e-commerce, based on our case study of Greece, a nation that has been slow to embrace Internet technologies.

Verifying security protocols for sensor networks using algebraic specification techniques

Algebraic specification languages are formal methods that provide a rigorous basis for modeling of several systems. Security protocols are safety critical systems that need to be verified before their implementation. In this paper we have formally specified sensor network encryption protocol (SNEP) and a key agreement protocol for sensor networks, both from the SPINS protocol suite, with the OTS/CafeOBJ method, a well known formal specification technique applied not only in research, but also in industry. Based on this specification, we have proved that each protocol possesses an important safety(invariant) property.

On the algebraic semantics of reactive rules

Service oriented architectures and event driven enviroments are becoming dominant over the web. Reactive Rules expressed by Rule Markup Languages are used to define the systems reactions. In this paper we present a Hidden (Sorted) Algebra approach to some of the most common families of Reactive Rules. This semantics will allow the mapping between Rule Markup Languages and Behavioral Algebraic Specification Languages. Verification techniques for reactive rules, will provide automated reasoning capabilities and support the development of new rule based policies and trust models.

Formal modeling and verification of sensor network encryption protocol in the OTS/CafeOBJ method

Sensor Network Encryption Protocol (SNEP) is one of the secure building blocks of the SPINS Protocol Suite and provides data confidentiality, two-party data authentication and evidence of data freshness in a wireless sensor network. We have formally analyzed SNEP and a node-to-node key agreement protocol based on it, using the OTS/CafeOBJ method. Among other invariants, we have verified that the protocols possess the important security properties of authenticity and confidentiality of relevant message components. To our knowledge, we are the first to formally analyze SNEP using algebraic specification techniques.

An Algebraic Framework for Modeling of Reactive Rule-Based Intelligent Agents

As the use of intelligent agents in critical domains increases, the need for verifying their behavior becomes stronger. Reactive rules are the main reasoning formalism for intelligent agents. For this reason, we propose the use of the OTS/CafeOBJ method for the specification of reactive rules, which will permit the verification of safety properties for reactive rule-based intelligent agents.

The Transposition of European Union Open Data/Public Sector Information Policies in Greece: A Critical Analysis

The successful implementation of the European Union (EU) public sector information (PSI) Directive and the relevant open data (OD) policies promises financial growth, social benefits, and the creation of jobs. While Greece has transposed all relevant EU Directives and has frequently made reference to the Digital Agenda for Europe: A Europe 2020 Initiative Agenda in its own policy documents, it has failed to implement effectively OD regulation and open up PSI. This failure may to a great extent be attributed to the absence of a middle layer of regulation between the law and standard public licenses; a regulatory vacuum that hinders both the operationalization of the law and the development of technological infrastructures, while managing to avoid being classified as a violation of the PSI Directive transposition. Using Lessigs four modalities of regulation, we conclude that the promised benefits of OD will only be achieved when all the necessary legal, technical, cultural, and economic regulatory elements are fully operational. Focusing merely on the opening up of data in the absence of the right financial and institutional conditions will not produce the desired results.

Extending standards with formal methods: Open Document Architecture

Formal methods, while very promising, are being adopted by software/protocol engineers very slowly, as the industry has little motivation to move into this new, unknown territory. At the same time, new industrial standards are being released quite frequently, as standardization seems to be very popular among developers. In this paper we present the idea of blending formal methods with industry standards. We claim that this results in more concrete system design and extended property verification tools. The enhancement of industry standards with formal methodologies leads to better understanding of the designed environment, eliminates ambiguity and forces a certain level of precision into the specification. An extra benefit is that we can use one of the many algebraic specification languages in order to assist with property checking/verification.