The Larch family of languages is used to specify program interfaces in a two-tiered definitional style. Each Larch specification has components written in two languages: one that is designed for a specific programming language and another that is independent of any programming language. The former are the Larch interface languages, and the latter is the Larch Shared Language (LSL). Version 2.3 of LSL is similar to previous versions, but contains a number of refinements based on experience writing specifications and developing tools to support the specification process. This report contains an informal introduction and a self-contained language definition. This report supersedes Pieces II and III of Larch in Five Easy Pieces [Guttag, Horning, and Wing 1985b] and "Report on the Larch Shared Language" [Guttag and Horning 1986]. iii Report on the Larch Shared Language, Version 2.3 Chapter 1: Overview 1.1. Introduction 1.2. Simple Algebraic Specifications 1.3. Getting Richer Theories 1.4...

: The structure of High-level nets is studied from an algebraic and a logical point of view using Algebraic nets as an example. First the category of Algebraic nets is defined and the semantics given through an unfolding construction. Other kinds of Highlevel net formalisms are then presented. It is shown that nets given in these formalisms can be transformed into equivalent Algebraic nets. Then the semantics of nets in terms of universal constructions is discussed. A definition of Algebraic nets in terms of structured transition systems is proposed. The semantics of the Algebraic net is then given as a free completion of this structured transition system to a category. As an alternative also a sheaf semantics of nets is examined. Here the semantics of the net arises as a limit of a diagram of sheaves. Next Algebraic nets are characterized as encodings of special morphisms called foldings. Each algebraic net gives rise to a surjective morphism between Petri nets and conversely each sur...

This paper presents a comparison between algebraic specifications-in-the-large and a type theoretical formulation of modular specifications, called deliverables. It is shown that the laws of module algebra can be translated to laws about deliverables which can be proved correct in type theory. The adequacy of the Extended Calculus of Constructions as a possible implementation of type theory is discussed and it is explained how the reformulation of the laws is influenced by this choice.