['Although', 'these', 'solutions', 'are', 'obtained', 'from', 'semi', '-', 'classical', 'arguments', 'in', 'weak', 'coupling', 'limit', ',', 'their', 'validity', 'as', 'quantal', 'states', 'is', 'justified', 'based', 'on', 'the', 'associated', 'topological', 'conservation', 'laws', '.']