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This text explores the concept of random numbers, defining them as unpredictable values derived from a process that cannot be reproduced. It differentiates between pseudo-random and true random number generators, illustrating examples and their mechanisms. Pseudo-random numbers utilize algorithms like the linear congruential method, while true random numbers extract randomness from physical phenomena such as radioactive decay or atmospheric noise. The importance of random numbers in cryptology, gaming, and sampling is also discussed, emphasizing their critical role in ensuring security and fairness across various applications.
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Definitions • Random number – a random number is a number that is generated by a process whose outcome is unpredictable and typically cannot be reproduced • Seed – starts the process for generating random numbers • Period – the length a given series of random numbers has before repeating a number
Types of Random Number Generators • Pseudo-Random Number Generators • Not truly random • True Random Number Generators • Extract randomness from physical phenomena
Pseudo-Random Number Generators • Linear congruential method • An example simple linear formula • Xn+1 <- (k*Xn + C) mod M • Sample sequence (k = 19, C = 51, M = 100, X0 = 25): • 25, 26, 45, 6, 47, 44, 87, 4, 27, 64, 67, 24, 7, 84, 47
True Random Number Generators • Need to use physical phenomena • Zener diode • Radioactive decay • Atmospheric noise/radio noise • Sample and convert to a 1 or 0
OH GOD MY BRAIN • Impossible to verify that a given number was produced randomly • Very easy to determine if a sequence of infinite length is random • Random if quantity of information it contains is also infinite
Applications of Random Numbers • Cryptology/Security • Game and gambling • Random Sampling (drug screening, exam questions) • Lotteries
References • http://www.random.org • A.K. Dewdney The (new) Turing omnibus, New York Henry Holt and Company