[tkuhn]

No, there can be contained URIs that are not trusty (probably the majority of contained URIs will be of that type). You can verify the entire reference tree as long as you follow trusty links, but of course this cannot go on indefinitely. Furthermore not all resources have the form of what I call a "digital artifact" (e.g. foaf:knows does not stand for a digital artifact), but they reach out to the real world (these URIs might not even return a representation, i.e. they might not be URLs).