Exercise 10.16 [satplan-preconditions-exercise]

Up to now we have assumed that the plans we create always make sure that an action’s preconditions are satisfied. Let us now investigate what propositional successor-state axioms such as ${HaveArrow}^{t+1} {\;\;{\Leftrightarrow}\;\;}{}$ $({HaveArrow}^t \land \lnot {Shoot}^t)$ have to say about actions whose preconditions are not satisfied.

  1. Show that the axioms predict that nothing will happen when an action is executed in a state where its preconditions are not satisfied.

  2. Consider a plan $p$ that contains the actions required to achieve a goal but also includes illegal actions. Is it the case that

  3. With first-order successor-state axioms in situation calculus, is it possible to prove that a plan containing illegal actions will achieve the goal?

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