In the above paper,1 an asymptotically tight upper bound on the th moment ( 0) of the minimal number of guesses required to determine the value of a random variable was derived. We show that we can tighten this bound for the case of positive integer moments (when = 1, the bound is improved by a factor of 2) and that the new bound also applies to a class of nonminimal guessing sequences.

OBJECTIVE To compare blinding integrity and associated factors for transcranial direct current stimulation (tDCS) vs. placebo-pill, the gold standard blinding method. METHODS Parallel trial. Depressed participants were randomized to verum/placebo sertraline and active/sham tDCS (2mA, 30-min 10-daily sessions and two additional, fortnight sessions) over 6weeks. Blinding was assessed in complet...

This paper provides upper and lower bounds on the optimal guessing moments of a random variable taking values on a finite set when side information may be available. These moments quantify the number of guesses required for correctly identifying the unknown object and, similarly to Arikan’s bounds, they are expressed in terms of the Arimoto-Rényi conditional entropy. Although Arikan’s bounds ar...

We study extrapolation between games in a laboratory experiment. Participants in our experiment first play either the dominance solvable guessing game or a Coordination version of the guessing game for five rounds. Afterwards they play a 3x3 normal form game for ten rounds with random matching which is either a game solvable through iterated elimination of dominated strategies (IEDS), a pure Co...

This work has been inspired by problems addressed in the field of computer security, where the attacking of, e.g., password systems is an important issue. In [2] Lundin et al. discuss measures related to the number of guesses or attemts a supposed attacker needs for revealing information. Similar problems are considered in [1], [3] and [4]. In this presentation numerical approaches are discusse...

Guessing, or dictionary, attacks arise when an intruder exploits the fact that certain data like passwords may have low entropy, i.e. stem from a small set of values. In the case of off-line guessing, in particular, the intruder may employ guessed values to analyze the messages he has observed. Previous attempts at formalizing off-line guessing consist of extending a Dolev-Yao-style intruder mo...

Passwords are widely used for user authentication, and will likely remain in use in the foreseeable future, despite several weaknesses. One important weakness is that human-generated passwords are far from being random, which makes them susceptible to guessing attacks. Understanding the adversaries capabilities for guessing attacks is a fundamental necessity for estimating their impact and advi...

We consider a game in which two separate laboratories collaborate to prepare a quantum system and are then asked to guess the outcome of a measurement performed by a third party in a random basis on that system. Intuitively, by the uncertainty principle and the monogamy of entanglement, the probability that both players simultaneously succeed in guessing the outcome correctly is bounded. We are...

Elementary results in algorithmic information theory are invoked to show that almost all finite functions are highly random. That is, the shortest program generating a given function description is rarely much shorter than the description. It is also shown that the length of a program for learning or optimization poses a bound on the algorithmic information it supplies about any description. Fo...

We consider a generalization of the standard oracle model in which the oracle acts on the target with a permutation which is selected according to internal random coins. We show new exponential quantum speedups which may be obtained over classical algorithms in this oracle model. Even stronger, we describe several problems which are impossible to solve classically but can be solved by a quantum...