Logical policy-based access control models are greatly expressive and thus provide the flexibility for administrators to represent a wide variety of authorization policies. Extensional access control models, on the other hand, utilize simple data structures to better enable a less trained and non-administrative workforce to participate in the day-to-day operations of the system. In this paper, ...

We define a higher-order extension of Datalog based on the Horn fragment of higher-order logic introduced in [Wad91]. Programs of Higher-Order Datalog can be understood declaratively as formulas in extensional higher-order logic, in which (for example) a unary predicate of unary predicates is a set of sets of data objects. The language retains all the basic principles of first-order logic progr...

Martin-Löf’s type theory is the basis of a variety of formal systems underlying many proof assistants. There are a lot of variants of type theory, among which two classes can be identified: intensional and extensional type theory. The difference between the two lies in the manner in which the equality is dealt with, but this results in huge differences. Intensional type theory requires the user...

Relational databases have had great industrial success in computer science. The power of the paradigm is made clear both by its widespread adoption and by theoretical analysis. Today, automated theorem provers are not able to take advantage of database query engines and therefore do not routinely leverage that source of power. Extensional Reasoning (ER) is an approach to automated theorem provi...

We define a translation that maps higher-order formulas provable in a classical extensional setting to semantically equivalent formulas provable in an intuitionistic intensional setting. For the classical extensional higher-order proof system we define a Henkincomplete tableau calculus. For the intuitionistic intensional higher-order proof system we give a natural deduction calculus. We prove t...

I show that Armstrong’s view of laws as second-order contingent relations of ‘necessitation’ among categorical properties faces a dilemma. The necessitation relation confers a relation of extensional inclusion (‘constant conjunction’) on its relata. It does so either necessarily or contingently. If necessarily, it is not a categorical relation (in the relevant sense). If contingently, then an e...

Information must have physical support and this physical universe comprises physical interactions. Hence actual information processes should have a description by interactions alone, i.e., an extensional description. In this paper, such a model of the process of information articulation from the universe is developed by generalizing the extensive measurement theory in metrology. Moreover, a mod...

This paper is mainly concerned with the RCC8 composition table entailed by the Region Connection Calculus (RCC), a well-known formalism for Qualitative Spatial Reasoning. This table has been independently generated by Egenhofer in the context of Geographic Information Systems. It has been known for some time that the table is not extensional for each RCC model. This paper however shows that the...