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الكلية كلية تكنولوجيا المعلومات
القسم قسم البرامجيات
المرحلة 3
أستاذ المادة إيمان صالح صكبان الرواشدي
2/27/2012 7:14:45 PM
5.8 Search Termination (Convergence Criteria) In short, the various stopping condition are listed as follows: • Maximum generations–The genetic algorithm stops when the specified number of generation’s have evolved. • Elapsed time–The genetic process will end when a specified time has elapsed. Note: If the maximum number of generation has been reached before the specified time has elapsed, the process will end. • No change in fitness–The genetic process will end if there is no change to the population’s best fitness for a specified number of generations. Note: If the maximum number of generation has been reached before the specified number of generation with no changes has been reached, the process will end. • Stall generations–The algorithm stops if there is no improvement in the objective function for a sequence of consecutive generations of length Stall generations. • Stall time limit–The algorithm stops if there is no improvement in the objective function during an interval of time in seconds equal to Stall time limit.
Example:Maximizing a Function Consider the problem of maximizing the function, f(x) = x2 where x is permitted to vary between 0 to 31. The steps involved in solving this problem are as follows: Step 1: For using genetic algorithms approach, one must first code the decision variable ‘x’ into a finite length string. Using a five bit (binary integer) unsigned integer, numbers between 0(00000) and 31(11111) can be obtained. The objective function here is f(x) = x2 which is to be maximized. A single generation of a genetic algorithm is performed here with encoding, selection, crossover and mutation. To start with, select initial population at random. Here initial population of size 4 is chosen, but any number of populations can be elected based on the requirement and application. Table 1. shows an initial population randomly selected.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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