L. D. E. F. Vesey-Fitzgerald

T L  C S C T F  O U L: E F P L  L D

A natural liberalization of Datalog is used in the Distributed Knowledge Authorization Language (DKAL). We show that the expressive power of this liberal Datalog is that of existential fixed-point logic. The exposition is self-contained.

O F F L I N E D E L E G a T I O N Offline Delegation

This article describes mechanisms for offline delegation of access rights to files maintained by a distributed “File Repository”. The mechanisms are designed for a target environment where personal machines are used at times when critical services, such as authentication and authorization services, are not accessible. We demonstrate how valid delegation credentials can be transferred verbally w...

WIND-CHILL E F F E C T F O R C A T T L E AND SHEEP t D. R. Ames and L. W. lnsley

Effective temperature is a term used to rate the cooling or heating power of the physical environment in terms of dry bulb temperature. For livestock exposed to cold, windy environments, effective temperature must now be predicted by a wind-chill index prepared for humans and designed without regard to extemal insulation_ suck~hai r or wool. The human wind-chill relationship is quadratic in nat...

T F L T C E  F L

We survey recent results on the enumeration of formal languages. In particular, we consider enumeration of regular languages accepted by deterministic and nondeterministic finite automata with n states, regular languages generated by regular expressions of a fixed length, and ω-regular languages accepted by Müller automata. We also survey the uncomputability of enumeration of context-free langu...

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