ai :: SearchProblem :: actions
While there is a potential large number of distinct states and actions, there should be only a small number of possible action from a specific state (a small, or at least finite, branching factor).
	# The available applicable actions for a given state.
	# While there is a potential large number of distinct states and actions, there should be only
	# a small number of possible action from a specific state (a small, or at least finite, branching factor).
	fun actions(state: S): nullable SequenceRead[A] is abstract
					lib/ai/search.nit:66,2--69,60
				
	# Get the four available movements, or 3 on a edge, or 2 in a corner.
	redef fun actions(state)
	do
		var h = get_hole(state)
		var x = h % width
		var y = h / width
		var res = new Array[Int]
		if x >= 1 then res.add(-1)
		if x < width-1 then res.add(1)
		if y >= 1 then res.add(-width)
		if y < width-1 then res.add(width)
		return res
	end
					lib/ai/examples/puzzle.nit:97,2--109,4