Objects with dynamic types allow the integration of operations that essentially require runtime type-checking into statically-typed languages. This article presents two extensions of the ML language with dynamics, based on our work on the CAML implementation of ML, and discusses their usefulness. The main novelty of this work is the combination of dynamics with polymorphism.

In this article, we discuss several possible extensions to traditional logic programming languages. The specic extensions proposed here fall into two categories: logical extensions and the addition of constructs to allow for increased control. There is a unifying theme to the proposed logical extensions, which is the scoped introduction of extensions to a programming context. More specically these extensions are the ability to introduce variables whose scope is limited to the term in which they occur (i.e. -bound variables within -terms), the ability to introduce into a goal a fresh constant whose scope is limited to the derivation of that goal, and the ability to introduce into a goal a program clause whose scope, once again, is limited to the derivation of that goal. The purpose of the additions for increased control are to facilitate the raising and handling of failures, or exceptions. and continuation thereafter. To motivate these various extensions, we have repeatedl...

At the Dolev-Yao level of abstraction, security protocols can be specified using multisets rewriting. Such rewriting can be modeled naturally using proof search in linear logic. The linear logic setting also provides a simple mechanism for generating nonces and session and encryption keys via eigenvariables. We illustrate several additional aspects of this direct encoding of protocols into logic. In particular, encrypted data can be seen naturally as an abstract data-type. Entailments between security protocols as linear logic theories can be surprisingly strong. We also illustrate how the wellknown connection in linear logic between bipolar formulas and general formulas can be used to show that the asynchronous model of communication given by multiset rewriting rules can be understood, more naturally as asynchronous process calculus (also represented directly as linear logic formulas). The familiar proof theoretic notion of interpolants can also serve to characterize communication between a role and its environment.

Logic programming can be given a foundation in sequent calculus by viewing computation as the process of building a cut-free sequent proof bottom-up. The first accounts of logic programming as proof search were given in classical and intuitionistic logic. Given that linear logic allows richer sequents and richer dynamics in the rewriting of sequents during proof search, it was inevitable that linear logic would be used to design new and more expressive logic programming languages. We overview how linear logic has been used to design such new languages and describe briefly some applications and implementation issues for them.