Abstract
Programming directly with diagrams offers potential advantages such as visual intuitions, identification of errors (debugging), and insight into the dynamics of the algorithm. the purpose of this paper is to put forward one particular graphical formalism, interaction nets, as a candidate for visual programming which has not only all the desired properties that one would expect, but also has other benefits as a language, for instance sharing computation.

Abstract

Abstract

Abstract
Token-passing nets were proposed by Sinot as a simple mechanism for encoding evaluation strategies for the ?-calculus in interaction nets. This work extends token-passing nets to cover a typed functional language equipped with structured types and unrestricted recursion. The resulting interaction system is derived systematically from the chosen big-step operational semantics. Along the way, we actually characterize and discuss several design decisions of token-passing nets and extend them in order to achieve simpler interaction net systems with a higher degree of embedded parallelism.

Abstract
This paper introduces INblobs, a visual tool developed at Minho for integrated development with Interaction Nets. Most of the existing tools take as input interaction nets and interaction rules represented in a textual format. INblobs is first of all a visual editor that allows users to edit interaction systems (both interaction nets and interaction rules) graphically, and to convert them to textual notation. This can then be used as input to other tools that implement reduction of nets. INblobs also allows the user to reduce nets within the tool, and includes a mechanism that automatically selects the next active pair to be reduced, following one of the given reduction strategies. The paper also describes other features of the tool, such as the creation of rules from pre-defined templates.

Abstract
Causality tracking mechanisms, such as vector clocks and version vectors, rely on mappings from globally unique identifiers to integer counters. In a system with a well known set of entities these ids can be preconfigured and given distinct positions in a vector or distinct names in a mapping. Id management is more problematic in dynamic systems, with large and highly variable number of entities, being worsened when network partitions occur. Present solutions for causality tracking are not appropriate to these increasingly common scenarios. In this paper we introduce Interval Tree Clocks, a novel causality tracking mechanism that can be used in scenarios with a dynamic number of entities, allowing a completely decentralized creation of processes/replicas without need for global identifiers or global coordination. The mechanism has a variable size representation that adapts automatically to the number of existing entities, growing or shrinking appropriately. The representation is so compact that the mechanism can even be considered for scenarios with a fixed number of entities, which makes it a general substitute for vector clocks and version vectors.