Iterative Planning with Plan-Space Explanations: A Tool and User Study
  In a variety of application settings, the user preference for a planning task
- the precise optimization objective - is difficult to elicit. One possible
remedy is planning as an iterative process, allowing the user to iteratively
refine and modify example plans. A key step to support such a process are
explanations, answering user questions about the current plan. In particular, a
relevant kind of question is "Why does the plan you suggest not satisfy $p$?",
where p is a plan property desirable to the user. Note that such a question
pertains to plan space, i.e., the set of possible alternative plans. Adopting
the recent approach to answer such questions in terms of plan-property
dependencies, here we implement a tool and user interface for human-guided
iterative planning including plan-space explanations. The tool runs in standard
Web browsers, and provides simple user interfaces for both developers and
users. We conduct a first user study, whose outcome indicates the usefulness of
plan-property dependency explanations in iterative planning.
