I think bentarm was offering "Combinatorics problems" as an example of the opposite of the phenomenon you describe. In particular the Four Colour Theorem is easy to formulate but hard to solve, and (as far as I know) the solution doesn't involve a reformulation.
Yes, upon re-reading I see that you are correct. I think there may be overlap between activities I consider part of the formulation and activities others may consider part of the solution.
To expand on my poker suggestion. When attempting to determine the probability of a hand in poker it is necessary to determine a way to represent that hand using combinations/permutations. I have found that for certain hands this can be rather difficult as you often miss, exclude, or double count some amount of possible hands. This process of representing the hand u...
Another monthly installment of the rationality quotes thread. The usual rules apply: