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Visual Debugger for Prolog Disclosure Number: IPCOM000058343D
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-15

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Morishita, S Numao, M Tozawa, Y Yokoi, S [+details]


This article describes an implementation technique of a visual debugger for Prolog. First, the idea of a visual debugger is introduced in comparison with a usual one. A visual debugger displays a computation of Prolog in Box and Plane Model (BPM) [*] notation, as shown in Fig. 1. The BPM plane contains the history of computation on that level and shows it in a visual way by using boxes and arrows. The user can, therefore, understand what has happened at a glance and take the short cut to a bug. (Image Omitted) In such a visual debugger, however, it was considered that the whole history should be saved so that the user could pick up any BPM plane and display it on the screen. A large memory area was consequently required. The proposed method here does not save the whole history.