Automatically Learning HTN Methods from Landmarks
This addresses the need for domain engineers in HTN planning by automating method learning, though it is incremental as it builds on HTN-MAKER.
The paper tackles the problem of automating HTN method learning by introducing CURRICULAMA, which eliminates manual input and achieves a convergence rate similar to HTN-MAKER.
Hierarchical Task Network (HTN) planning usually requires a domain engineer to provide manual input about how to decompose a planning problem. Even HTN-MAKER, a well-known method-learning algorithm, requires a domain engineer to annotate the tasks with information about what to learn. We introduce CURRICULAMA, an HTN method learning algorithm that completely automates the learning process. It uses landmark analysis to compose annotated tasks and leverages curriculum learning to order the learning of methods from simpler to more complex. This eliminates the need for manual input, resolving a core issue with HTN-MAKER. We prove CURRICULAMA's soundness, and show experimentally that it has a substantially similar convergence rate in learning a complete set of methods to HTN-MAKER.