Strips –Stands for STanford Research Institute Problem Solver (1971).
STRIPS Pseudo code -
STRIPS(stateListstart, stateListgoals)1.Set state = start2.Set plan = []3.Set stack = goals4.while stack is not empty do 1.STRIPS-Step()5.Return planSTRIPS-Step()switch top of stack t:1.case this a goal that matches state: 1.pop stack2.case this an unsatisfied conjunctive-goal: 1.select an ordering for the sub-goals 2.push the sub-goals into stack3.case this a simple unsatisfied goal 1.choose an operator op whose add-list matches t 2.replace the twith op 3.push preconditions of op to stack4.case this an operator 1.pop stack 2.state = state + t.add-list -t.delete-list 3.plan = [plan | t]Some explanations -
state - is a list of predicates.
stack - is a stack which includes both predicates or operations.
[plan | t] - add the opreration t to list plan.
If the stack gets empty, it means that plan holds the solution plan.
Since the algorithm is running while stack is not empty do, how can I recognize that there is no solution (i.e plan) which led to the goal state ?
Those who are not familiar with this algorithm, you can see its running example here. Brief introduction: imagine a crane which picks boxes and put them each other , so operation can be put box A on box B and state can be box A is on box B .
