On the Impossibility of Learning the Missing Mass

Autor: Elchanan Mossel, Mesrob I. Ohannessian
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Zdroj: Entropy, Vol 21, Iss 1, p 28 (2019)
Druh dokumentu: article
ISSN: 1099-4300
DOI: 10.3390/e21010028
Popis: This paper shows that one cannot learn the probability of rare events without imposing further structural assumptions. The event of interest is that of obtaining an outcome outside the coverage of an i.i.d. sample from a discrete distribution. The probability of this event is referred to as the “missing mass”. The impossibility result can then be stated as: the missing mass is not distribution-free learnable in relative error. The proof is semi-constructive and relies on a coupling argument using a dithered geometric distribution. Via a reduction, this impossibility also extends to both discrete and continuous tail estimation. These results formalize the folklore that in order to predict rare events without restrictive modeling, one necessarily needs distributions with “heavy tails”.
Databáze: Directory of Open Access Journals
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