  When generating technical instructions, it is often convenient to describe
complex objects in the world at different levels of abstraction. A novice user
might need an object explained piece by piece, while for an expert, talking
about the complex object (e.g. a wall or railing) directly may be more succinct
and efficient. We show how to generate building instructions at different
levels of abstraction in Minecraft. We introduce the use of hierarchical
planning to this end, a method from AI planning which can capture the structure
of complex objects neatly. A crowdsourcing evaluation shows that the choice of
abstraction level matters to users, and that an abstraction strategy which
balances low-level and high-level object descriptions compares favorably to
ones which don't.
