[bryanrasmussen]

ok but if the coin tends to land as starting then

1. starting from heads

2. flip heads

3. flip heads

4. starting from heads

5. flip heads

6. flip tails

take 5 = heads?

heads should still be more likely to occur than tails under this scenario, although, Zeno-like, with decreasing likelihood approaching zero over time?

on edit: of course Von Neumann's process has more restrictions, leading closer to fairness.

[raphael_kimmig]

If you always start with heads the method works out. The key is that the first and the second toss need to be independent so that HT and TH have the same probability. If you influence the second toss based on the first one it no longer works.