# Various Map implementations of memory.
	# In order to try more configurations with `run_config`, this method
	# is called to provide alternative implementation.
	#
	# For instance, a subclass can redefine this method and extends the result with an additional `RBTreeMap`.
	# Note: because the true nature of the sates `S` is left to the user, some
	# specific Map implementation could be more efficient than a HashMop.
	#
	# Default: A `HashMap`
	fun make_memory: Array[Map[S, SearchNode[S, A]]]
	do
		var res = new Array[Map[S, SearchNode[S, A]]]
		res.add new HashMap[S, SearchNode[S, A]]
		return res
	end