Kahina , a Debugging Framework for Logic Programs and TRALE

Abstract

We present a new graphical debugging framework, Kahina, for logic programming and demonstrate two of its key features by applying it to debugging HPSG grammars in TRALE (Penn et al., 2003). Debugging TRALE grammars, such as those presented in the textbook by M¨ uller (2007), that stay true to their declarative specification in HPSG is a particularly challenging logic programming task, due to the size and complexity of these grammars. Kahina visualizes the structure of the parse pro- cess as a tree and relates each action to the grammar’s source code, making it possible to maintain an overview over a large number of steps. The debugger lets users inspect each parse step with its complete context (variable bindings, executed constraints on feature structures, and effects of proce- dural attachments), thereby providing all information necessary to understand complex interactions of different grammar components that are otherwise very hard to discern. A novel and versatile breakpoint system based on tree automata permits precise searches for specific events during parsing.