A common constraint in logic problems is the one restricting questions you may ask to those that can only be helpfully answered with a "yes" or "no".
But in some cases, you might ask someone a question where "yes" or "no" are the only answers if you know the answer, but where some respondents may lack the necessary information to know.
Example: You meet one "truth-teller" and one "random-respondent", who is "50-50" to reply yes or no to any given question. You don't know who's who, but they do. If you're limited to "yes/no" questions, can you ask one of them what the other person would say? (The problem is that the truth-teller doesn't know, and knows he doesn't know; his only possible honest answer is "I don't know."
What, if anything are the conventions in cases where "yes/no" is a constraint, but the issue of questions the respondent can't answer is not explicitly addressed? Presumably, they must fall into one of the following:
- You're not allowed to ask a question where the respondent might not be able to reply. This is simple, but... seems somehow more odd to me than the other arbitrary ridiculous rules, although I have no idea why that is.
- You are allowed to ask questions like that, in which case, you must also assume they are allowed to convey "I don't know" (assume they have a veracity type that would make them honest).
I was deliberately using a simple example, but the puzzle that this comment is on is what inspired the question. (I haven't solved it yet, so please don't share whether it's relevant to that particular solution; I'm more interested in what assumptions, if any are generally applied to other problems like this.