11.5 Mission Planning

STRIPS is a general solver which was based on the General Problem Solver and refined by Stanford.

in Strips a problem is composed of

1. Initial state
2. Goal state
3. Actions with Preconditions and Postconditions

Formally, a STRIPS problem is a quadruple $<P,O,I,G>$

• $P$ is the set of propositional variables that can either be true or false and exhaustively describe the world the robot operates in.
• $O$ is a set of operators, each itself a quadruple $<\alpha ,\beta ,\gamma ,\delta >$, whose entries determine the set of conditions that need to be true ($\alpha$) and that need to be false ($\beta$), for the action to take place, and a set of conditions that will be true ($\gamma$) and that will be false ($\delta$) if the action is successful.
• $I$ is a set of conditions $I\subset P$ that are initially true and define the initial state, all other conditions are initially false.
• $G$ is a tuple $<N,M>$ in which $N$ is a set of conditions that need ot be true and $M$ is a set of conditions that need to be false.

With no other bells and whistles defining a problem in this manner can get tricky quickly (the devil is in the details)

it is common to add parameterized locations and objects.