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# compound tasks (intermediate state), which can be seen as composed of a set of simpler tasks;
# goal tasks (goal state), which roughly corresponds to the goals of STRIPS, but are more general.

A solution to an HTN problem is then an executable sequence of primitive tasks that can be obtained from the initial task network by decomposing compound tasks into their set of simpler tasks, and by inserting ordering constraints.

A primitive task is an action that

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