[jmcqk6]

Libertarians do overlap quite a bit with anarcho-capatilism and randism. You might not define libertarianism that way, but many do. The best you might say is something like, 'libertarianism, as espoused by [X], hold that a government should be in place.' As a counter example, I can easily find self-identified libertarians who are anarchists.

edit: grammar and clarification.