Quote:
Originally Posted by lisa
Sometimes you can check something very quickly that can take a long time to figure out... a reverse-hash, for example.
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An example. Take the phrase "ABCD". It is described by the number 61626364. Divide that number by a prime. The resulting encryption might be 635323 and 33.
Did that encryption algorithm work? Trying to reserve the hash using brute force takes long. Reversing the hash to check it is fast.
635323 times 97 is 61626331. Add 33 to confirm 61626364.
In this case, a reverse hash can easily verify the hash.
Rumors from observation claim that every Freecell game is winnable. But it has not been proven. The brute force method is to play every possible game. But no reverse process can prove that conclusion.
Some solutions are easily confirmed by reversing the process. Others are not.
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IBM et al are not criticizing the Google machine (as so many assumed due to conclusions from soundbyte reasoning). They are criticizing a calculation that a conventional super computer could take 10,000 years to solve that problem. That conclusion assumed limited memory. With expanded memory, IBM, et al conclude the problem could be solved in 2.5 days. Using quantum computing, then not so much conventional memory is necessary.
Simple another step in the process of taking a theory, through fundamental research, into application research, and then into commercial products.