Quote from: btchris on October 15, 2014, 12:55:47 AM

Quote from: qdoop on October 15, 2014, 12:14:29 AM

This is clear and thank you for clarifying! A bit shift modifies possibility by 50%.

Yes, but the hash target doesn't necessarily move from 135 bits to 136 bits, it moves from 135.1 to 135.4.

Quote from: qdoop on October 15, 2014, 12:14:29 AM

Just a question if you know for sure. When calculating the total difficulty of a chain we count the values of the actual hashes or the difficulty targets in the blocks?

The total difficulty of a chain (for the purposes of determining which chain is longest) is the sum of the difficulty targets, and has nothing to do with the "luck" of the miners / block hashes.

Thanks a lot!
Seems you have practiced a lot with difficulty and to tell you the truth my motivation was for a simpler way to model it using two numbers.
Bit transitions, dominant zeros and just pure binary operations without any large number maths involved.

PS. Was really nice sharing your opinions with me. An other interesting subject is the +2/-1 hours range for block inclusion in a chain. Does exist an alternative?