What is the value of just a few bits Mini Dress to a guesser? We study this problem in a setup where Alice wishes to guess an independent and identically distributed (i.i.d.
) random vector and can procure a fixed number of k information bits from Bob, who has observed this vector through a memoryless channel.We are interested in the guessing ratio, which we define as the ratio of Alice’s guessing-moments with and without observing Bob’s bits.For the case of a uniform binary vector observed through a binary symmetric channel, we provide two upper bounds on the guessing ratio by analyzing the performance of the dictator (for general k ≥ 1 ) and majority functions (for k = 1 ).
We further provide a lower bound via maximum entropy (for general k ≥ 1 ) and a lower bound based on Fourier-analytic/hypercontractivity arguments (for k = 1 ).We then extend our maximum entropy argument to give a lower bound on the guessing ratio for a general channel with a binary uniform input that is expressed using the strong data-processing inequality constant of the reverse channel.We compute this bound for Bookends the binary erasure channel and conjecture that greedy dictator functions achieve the optimal guessing ratio.