Longbow

Longbow is a hierarchical discourse planning system that combines decompositional reasoning (planning to perform an abstract action by performing that action's substeps) and causal reasoning (planning to perform an action by ensuring that the action's preconditions all hold before its execution) in the same representation.

The Longbow system is based on a domain-independent hierarchical AI planning algorithm named DPOCL (Decompositional, Partial-Order Causal Link planner) which itself is built on top of a non-hierarchical planner, UCPOP. Longbow differs from DPOCL and UCPOP by containing extensions that make representing communicative actions possible.

Highlights of Longbow's Feature List include:

Longbow's extended plan representation includes:
- the intentional and informational structure of a discourse, represented in a clean and precise manner.
- communicative actions with multiple effects.
- tree-structured plans as well as graph-structured plans (that is, discourse plans that share components between distinct segments).
- plans with interleaved subplans (that is, discourse plans that interleave communicative actions from distinct segments).
- a flexible recipe-writing language allowing the operator writer to specify complete recipes, empty recipes or partial recipes.
Longbow's planning algorithm provides:
- reasoning that combines hierarchical and causal planning.
- a plan-space search function, making debugging more straightforward.
- a provably sound and complete planner.
- the ability to include user-defined and domain-specific search-control knowledge distinct from the planning algorithm.
- easy integration with external knowledge bases.
- graphical user interfaces being developed for CLIM 2.0 and the Macintosh Common Lisp and ACL/PC user interface packages.

Please send any comments related to Longbow to longbow@liquidnarrative.csc.ncsu.edu . Any comments on the content and structure of the Longbow web should be sent to young@csc.ncsu.edu