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SLDNF-Draw: a Visualisation Tool of Prolog Operational Semantics

Logic Programming is a programming paradigm widely used for teaching Artificial Intelligence in university courses. Also, learning it is propaedeutical for understanding formal specification languages, widely accepted tools in software engineering. Many widely used Logic Programming languages (such as Prolog) adopt the SLDNF resolution as operational semantics. However, after a first phase in which students learn how specifications can be translated into executable code, a second phase is necessary for engineering the resulting program. In this second phase, having a clear picture of the execution model is crucial. In this paper, SLDNF-Draw, a program that visualises the SLDNF operational semantics, is presented. It has been successfully used in university courses to support teaching of Prolog.