Hi major, I just read your post and its great, thank you, it really has inspired me to learn more on erasure codes. I only have one doubt: in the Example Problem, I understand the 4th parity bit should be the 8th position (starting the first at 1), however you placed it in the 9th position, and I think this is the reason why (according to me) in the 2nd parity check the bit should be 1 instead of 0, however your answer was still right, so could you tell me what is the correct place for the 4th parity bit?