I know that we can visualize a Non deterministic TM as a TM which splits into multiple copies of itself whenever it sees a non deterministic path (Yes, I also know that this is just a visualization and is usually used by beginners like me for understanding non determistisism).
Further, I also know that a Decider is a TM that halts on all possible inputs.
Now, my question is how can I visualize a Non determistic Decider? Does a non-determistic decider mean a TM where
- All the copies must halt, (OR)
- At-least one copy halts.
Kindly explain in detail why so. Thanks.