[zzzcpan]

> by generating more than 2^B UUIDs on the same machine within a fairly short timeframe and fairly large B

Which can be made impossible.

IDs are part of the finite system and don't exist on their own. And the system can perform a finite number of operations both concurrently and in a finite time-interval with some amount of uniqueness distinguishing nodes and other useful properties. Making it possible to always find an id generating algorithm for this system that can never have collisions.

[firebacon]

I agree, if we are allowed to make the UUID arbitrarily large (and not be limited to the 128 bits from the "official" UUID algorithm), it should always be possible to set B to a large enough value so that our scheme assigns a unique and finite-sized UUID to every possible state of the system, since all the system's parameters (number of servers, time, etc) should be discrete and finite. I.e. basically make B large enough that 2^B becomes greater than the number of discrete timesteps in our experiment. That's an interesting observation.

[zzzcpan]

You can get away with a lot less than 128 bits for most systems. It's only that big because it tries to be universal.