Maude: specification and programming in rewriting logic

Maude is a high-level language and a high-performance system supporting executable specification and declarative programming in rewriting logic. Since rewriting logic contains equational logic, Maude also supports equational specification and programming in its sublanguage of functional modules and theories. The underlying equational logic chosen for Maude is membership equational logic, that has sorts, subsorts, operator overloading, and partiality definable by membership and equality conditions. Rewriting logic is reflective, in the sense of being able to express its own metalevel at the object level. Reflection is systematically exploited in Maude endowing the language with powerful metaprogramming capabilities, including both user-definable module operations and declarative strategies to guide the deduction process. This paper explains and illustrates with examples the main concepts of Maude's language design, including its underlying logic, functional, system and object-oriented modules, as well as parameterized modules, theories, and views. We also explain how Maude supports reflection, metaprogramming and internal strategies. The paper outlines the principles underlying the Maude system implementation, including its semicompilation techniques. We conclude with some remarks about applications, work on a formal environment for Maude, and a mobile language extension of Maude

Bayesian Decision Theory and Stochastic Independence

Stochastic independence has a complex status in probability theory. It is not part of the definition of a probability measure, but it is nonetheless an essential property for the mathematical development of this theory. Bayesian decision theorists such as Savage can be criticized for being silent about stochastic independence. From their current preference axioms, they can derive no more than the definitional properties of a probability measure. In a new framework of twofold uncertainty, we introduce preference axioms that entail not only these definitional properties, but also the stochastic independence of the two sources of uncertainty. This goes some way towards filling a curious lacuna in Bayesian decision theory

Quantum value indefiniteness

The indeterministic outcome of a measurement of an individual quantum is certified by the impossibility of the simultaneous, definite, deterministic pre-existence of all conceivable observables from physical conditions of that quantum alone. We discuss possible interpretations and consequences for quantum oracles.Comment: 19 pages, 2 tables, 2 figures; contribution to PC0

On the relation between plausibility logic and the maximum-entropy principle: a numerical study

What is the relationship between plausibility logic and the principle of maximum entropy? When does the principle give unreasonable or wrong results? When is it appropriate to use the rule `expectation = average'? Can plausibility logic give the same answers as the principle, and better answers if those of the principle are unreasonable? To try to answer these questions, this study offers a numerical collection of plausibility distributions given by the maximum-entropy principle and by plausibility logic for a set of fifteen simple problems: throwing dice.Comment: 24 pages of main text and references, 8 pages of tables, 7 pages of additional reference

Towards Intelligent Databases

This article is a presentation of the objectives and techniques of deductive databases. The deductive approach to databases aims at extending with intensional definitions other database paradigms that describe applications extensionaUy. We first show how constructive specifications can be expressed with deduction rules, and how normative conditions can be defined using integrity constraints. We outline the principles of bottom-up and top-down query answering procedures and present the techniques used for integrity checking. We then argue that it is often desirable to manage with a database system not only database applications, but also specifications of system components. We present such meta-level specifications and discuss their advantages over conventional approaches

Technocracy inside the rule of law : challenges in the foundations of legal norms

Technocracy is usually opposed to democracy. Here, another perspective is taken: technocracy is countered with the rule of law. In trying to understand the contemporary dynamics of the rule of law, two main types of legal systems (in a broad sense) have to be distinguished: firstly, the legal norm, studied by the science of law; secondly, the scientific laws (which includes the legalities of the different sciences and communities). They both contain normative prescriptions. But their differ in their subjects‘ source: while legal norms are the will’s expression of the normative authority, technical prescriptions can be derived from scientific laws, which are grounded over the commonly supposed objectivity of the scientific knowledge about reality. They both impose sanctions too, but in the legal norm they refer to what is established by the norm itself, while in the scientific legality they consist in the reward or the punishment derived from the efficacy or inefficacy to reach the end pursued by the action. The way of legitimation also differs: while legal norms have to have followed the formal procedures and must not have contravened any fundamental right, technical norms‘ validity depend on its theoretical foundations or on its efficacy. Nowadays, scientific knowledge has become and important feature in policy-making. Contradictions can arise between these legal systems. These conflicts are specially grave when the recognition or exercise of fundamental rights is instrumentally used, or when they are violated in order to increase the policies‘ efficacy. A political system is technocratic, when, in case of contradiction, the scientific law finally prevails

Audit-based Compliance Control (AC2) for EHR Systems

Traditionally, medical data is stored and processed using paper-based files. Recently, medical facilities have started to store, access and exchange medical data in digital form. The drivers for this change are mainly demands for cost reduction, and higher quality of health care. The main concerns when dealing with medical data are availability and confidentiality. Unavailability (even temporary) of medical data is expensive. Physicians may not be able to diagnose patients correctly, or they may have to repeat exams, adding to the overall costs of health care. In extreme cases availability of medical data can even be a matter of life or death. On the other hand, confidentiality of medical data is also important. Legislation requires medical facilities to observe the privacy of the patients, and states that patients have a final say on whether or not their medical data can be processed or not. Moreover, if physicians, or their EHR systems, are not trusted by the patients, for instance because of frequent privacy breaches, then patients may refuse to submit (correct) information, complicating the work of the physicians greatly. \ud \ud In traditional data protection systems, confidentiality and availability are conflicting requirements. The more data protection methods are applied to shield data from outsiders the more likely it becomes that authorized persons will not get access to the data in time. Consider for example, a password verification service that is temporarily not available, an access pass that someone forgot to bring, and so on. In this report we discuss a novel approach to data protection, Audit-based Compliance Control (AC2), and we argue that it is particularly suited for application in EHR systems. In AC2, a-priori access control is minimized to the mere authentication of users and objects, and their basic authorizations. More complex security procedures, such as checking user compliance to policies, are performed a-posteriori by using a formal and automated auditing mechanism. To support our claim we discuss legislation concerning the processing of health records, and we formalize a scenario involving medical personnel and a basic EHR system to show how AC2 can be used in practice. \ud \ud This report is based on previous work (Dekker & Etalle 2006) where we assessed the applicability of a-posteriori access control in a health care scenario. A more technically detailed article about AC2 recently appeared in the IJIS journal, where we focussed however on collaborative work environments (Cederquist, Corin, Dekker, Etalle, & Hartog, 2007). In this report we first provide background and related work before explaining the principal components of the AC2 framework. Moreover we model a detailed EHR case study to show its operation in practice. We conclude by discussing how this framework meets current trends in healthcare and by highlighting the main advantages and drawbacks of using an a-posteriori access control mechanism as opposed to more traditional access control mechanisms

A Survey of Paraphrasing and Textual Entailment Methods

Paraphrasing methods recognize, generate, or extract phrases, sentences, or longer natural language expressions that convey almost the same information. Textual entailment methods, on the other hand, recognize, generate, or extract pairs of natural language expressions, such that a human who reads (and trusts) the first element of a pair would most likely infer that the other element is also true. Paraphrasing can be seen as bidirectional textual entailment and methods from the two areas are often similar. Both kinds of methods are useful, at least in principle, in a wide range of natural language processing applications, including question answering, summarization, text generation, and machine translation. We summarize key ideas from the two areas by considering in turn recognition, generation, and extraction methods, also pointing to prominent articles and resources.Comment: Technical Report, Natural Language Processing Group, Department of Informatics, Athens University of Economics and Business, Greece, 201