L02_HashMDMAC

Is the birthday paradox in a room with n people what

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Unformatted text preview: is. is. The Birthday Paradox In a room with n people, what is the probability that we will In find at least 2 people who have the same birthday (there are m = 365 possible choices of birthday)? An approximate analysis: An approximate Assuming birthdays are uniformly distributed over the Assuming entire year. For any given pair of people, the possibly of them having the same birthday is 1/m = 1/365 ; them There are nC2 = n(n-1)/ 2 ways to select a pair out of n There people people Let Pcollision be the Probability of at least one collision, P collision approx. = n(n-1)/2 * 1/m = n(n-1)/2m ; Pcollision > ½ when n >= 20 In general, Pcollision > ½ when n becomes >= √ m In The approximation is not good when n approaches m Where is the approximation ? The Birthday Paradox (cont’d) In a room with n people, what is the probability that we will In find at least 2 people who have the same birthday (there are m = 365 possible choices of birthday)? 365 An exact analysis: An exact Assuming birthdays are uniformly distributed over the Assuming e...
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This note was uploaded on 12/05/2013 for the course IERG 4130 taught by Professor Chowsze-ming,sherman during the Fall '13 term at CUHK.

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