[Const-me]

Sure, it’s an abstract machine invented to research mathematical model of computation.

I’d like to point out, the very moment you hooked second asynchronously moving head to the machine, the abstraction leaked spectacularly. With two asynchronous heads, the machine no longer has state; suddenly we need to consider physical time, not just count steps; and so on.

Turing machine is useful abstraction for sequential computing, but nearly useless to research parallel computing problems. The same happens with many other abstractions and approaches when going parallel.

> either one of those moves completes before the other

Yeah, but in parallel computing, we don’t know that order, and have no way of knowing. Meaning the “sequence of state transitions” idea is IMO nearly useless.