Using Heuristic Search to Retrieve Cases that Support Arguments

Indexing and Retrieval

We discuss the use of heuristic search in a graph of cases and other domain knowledge to supply support for an argument. We contend that for legal argument, a gap exists between the vocabulary of constraints upon arguments and the indexing vocabulary for cases and other domain resource knowledge. We suggest best-first search of a graph of cases and other domain knowledge as a means to partially close this gap. In particular, search of the case-domain graph is driven by one of three evaluation functions that use different levels of abstraction to mediate between the indexing vocabulary and the task vocabulary. We describe the BankXX system, which uses heuristic search to retrieve cases and other domain knowledge in support of an argument.