[chr1]

I don't know of any good definition of free will, intuitively it should be something that would allow to say "this person made a choice and that choice wasn't something that i could predict simply with some machine or equation".

Say the system is deterministic, and we have the technical ability to perfectly predict its future. There are several ways to predict that future, for instance for a dropped stone, we simply put a number into a simple formula and get the position, for water flow we have to compute some integrals. In both cases what we do, is not exactly equivalent to the process we are trying to simulate, and we omit all the things that happen during the process. My conjecture is that for a system containing a person, the computation is irreducible, and the only way to predict the future is to simulate it with 100% faithfulness which makes the process of prediction equivalent to that person living an making a choice.

This explains the paradox of god knowing everything, but people making their own choices, because even though all the information about the future exists at current time, the only way to extract that information is to let people live and see what they do.

The system being indeterministic doesn't seem to give a more useful interpretation to the vague definition above. It either doesn't fully describe the person (something from outside the system makes the choice like in games), or adds some randomness to the choice.

Do you know a better definition of free will?

[zaat]

I don't find any definition of free will as coherent, so I don't have any favorite one, but I don't see how the definition you proposed carries the common properties associated with free will, for an instance the list of properties mentioned at the beginning of the original article.