Bitcoin Forum

I have been trying to come up with an alternative proof of work allowing arbitrary calculations to be performed instead of hashing.

I blv I have a way to combine blockchain protection with e.g. folding (or any other difficult operation)
In case of proteins, based on a large library of proteins to be folded, in case of any other calculation a (large) library of such calculations.

The idea employs a blockchain just as btc except that the hash of
(transactions in the current block+hash of previous block)
is used to choose a problem from the library.  The lowest energy solution (for proteins, or best/only solution for other problems) is sought.
Whoever comes up with lowest local minimum within 10-minute block time gets block reward.

(solution + transactions + hash of previous block)
are hashed together for the next block a-la bitcoin.  Faking a block is now similarly difficult.
A bit more detail here http://telavivmakers.org/index.php/Protein_coin (http://telavivmakers.org/index.php/Protein_coin) - including way to allow users to design algorithms yet prevent best coder/folder from gaining control.

"Whoever comes up with lowest local minimum within 10-minute block time gets block reward."

How do you get around the need for synchronization, or detect someone spoofing the timestamp?

ya its a good point, consider otoh that the blockchain notion came from the 'timestamp server' which is just that which proves that a given operation was performed after time t, while what  would be needed is a way to prove that a given operation was performed before  time t

To be usable as alternative proof of work your proposal must have the fundamental property to be fast and easy to check if a solution is valid and of course that finding the solution is arbitrarily hard.

I understand what folding proteins is about, but I don't see how it applies to the needed properties as proof of work.

How can you proove fast that a submitted solution is actually one that is valid compared to other submissions?

The valid folds are required to be local minima of the folding energy landscape.
These are easy to check (taking O(K) cycles in a K-dimensional landscape) but hard to find (taking something like O(A^K) cycles).

its an interesting puzzle
using a blockchain one can verify that a given block comes before a second, and if the second is timestamped
e.g. using a timestamp server
then the second definitely came before something that comes after time t...which tells you nothing about the timing