3 ms·

Very interesting thought experiment. A few random thoughts: Reminds me of Panoptic by the EFF: https://panopticlick.eff.org/ https://panopticlick.eff.org/ Eve

Very interesting thought experiment. A few random thoughts: Reminds me of Panoptic by the EFF: https://panopticlick.eff.org/ https://panopticlick.eff.org/ Everyone's ID would change as time passed (if they move, if they age, if they get a sex change, etc). The best questions for this are inherently "irrelevant", since "relevant" questions tend to be statistically linked. So, questions like "Was the second letter of your first girlfriend's middle name between A and M?" is better than "Were you younger than 20 when you had your first girlfriend?", since we can likely guess the latter based on the other statistics. It's very unlikely every ID will be unique if only asking 33 yes/no questions. I mean, look at two twins living together -- very few questions will be able to differentiate between them. I think it's possible to do based on a random snapshot in time, however less possible if it's meant to last a lifetime. I also think the questions exist, but not in a manner that we'd be able to come up with on our own. As in, I believe that a program that knew every detail about every human could create 33 yes/no questions that differentiated people, however I don't believe we could do it ourselves. I also wonder how many questions would be required to ask non-yes/no questions and get a completely unique ID for everyone. For example, questions like "weight? languages spoken? birth place?".

deleted 13y ago
[deleted]
buo 13y ago
If you allow questions with n possible answers, then you need at least ceil(log_n(7e9)) questions, where log_n means logarithm base n. I don't know if there is a simple formula for the case where different questions allow different number of answers.
Scarblac 13y ago
But""Was the second letter of your first girlfriend's middle name between A and M?" is a bad question on many levels -- people who aren't attracted to females, people who are but have never had a girlfriend (including children), people who got married to their wife as the start of the relationship, and cultures where "girlfriend" would be hard to define because of that sort of thing. I can think of almost perfectly 50/50 questions based on odd/evenness of numbers (is your current weight in grams/age in hours/number of hairs odd or even) but those are completely time dependent.
PeterisP 13y ago
Only ~1/3 of population would even be able to answer a question like "Was the second letter of your first girlfriend's middle name between A and M?". 26% of global people are pre-teens; and approx half of the remainder aren't dating women. Not even going into the fact that the social concept of 'girlfriend' isn't universal, there are multimillion cultures where the relationship stages of going from strangers to family are split differently, and none of those stages can be equated with western 'boyfriend/girlfriend' relationship; e.g. you may like someone but not be dating (so no girlfriend) and then move directly to engagement or marriage; or many other possibilities.
gkoberger 13y ago
[EDIT] I should have said "significant other", not "girlfriend". Even then, it doesn't work -- but at least it's more inclusive :)

deleted 13y ago

[deleted]

buo 13y ago

If you allow questions with n possible answers, then you need at least ceil(log_n(7e9)) questions, where log_n means logarithm base n. I don't know if there is a simple formula for the case where different questions allow different number of answers.

Scarblac 13y ago

But""Was the second letter of your first girlfriend's middle name between A and M?" is a bad question on many levels -- people who aren't attracted to females, people who are but have never had a girlfriend (including children), people who got married to their wife as the start of the relationship, and cultures where "girlfriend" would be hard to define because of that sort of thing. I can think of almost perfectly 50/50 questions based on odd/evenness of numbers (is your current weight in grams/age in hours/number of hairs odd or even) but those are completely time dependent.

PeterisP 13y ago

Only ~1/3 of population would even be able to answer a question like "Was the second letter of your first girlfriend's middle name between A and M?". 26% of global people are pre-teens; and approx half of the remainder aren't dating women. Not even going into the fact that the social concept of 'girlfriend' isn't universal, there are multimillion cultures where the relationship stages of going from strangers to family are split differently, and none of those stages can be equated with western 'boyfriend/girlfriend' relationship; e.g. you may like someone but not be dating (so no girlfriend) and then move directly to engagement or marriage; or many other possibilities.

gkoberger 13y ago

[EDIT] I should have said "significant other", not "girlfriend". Even then, it doesn't work -- but at least it's more inclusive :)