An example of how you could fill this in: identify a small subset of the problem that is relatively quick and easy to test. If the entirety of the problem can be solved, then for sure this small subset has to be solvable too. If you can't solve this small sub-problem, then you know there's not much point diving into the larger rabbit hole yet. However if you do solve the sub-problem, then that might show you the potential that exists, it may allow you to already look at adjacent problems using the results of this early test, and also important: it will give you additional motivation to keep going.
