"Bill Denton" wrote in message ...
As separation is a function of traffic control, when would traffic control
not include separation?

When not specifically provided. ATC is a set of services. Not all are provided
to all people at all times.

IFR aircraft are separated from other IFR in controlled airspace.
Everybody gets seperated in class A and B.
VFR's get seperated in class C (and in the adjacent airspace) when in radio and radar contact.

Otherwise there is no separation service provided.

How is a tower going to provide separation to a bunch of VFR's that are buzzing around
with the sole requirement that they were talking to him?

Who would be responsible for separation and sequencing under these
circumstances?

You knew the answer to that. The responsibility falls on the pilot in command.