يک الگوريتم جديد مبتني بر آتاماتاي يادگير توزيع‌شده توسعه‌يافته براي يادگيري پارامتري شبکه بيزي
محورهای موضوعی : مهندسی برق و کامپیوترمحمدرضا ملاخلیلی میبدی 1 , محمدرضا میبدی 2
1 - دانشگاه آزاد اسلامی، واحد میبد
2 - دانشگاه صنعتی امیرکبیر
کلید واژه: آتاماتاي يادگير شبکه بيزي يادگيري پارامتري,
چکیده مقاله :
در اين مقاله يک آتاماتاي توزيع‌شده جديد به نام آتاماتاي يادگير توزيع‌شده توسعه‌يافته براي يادگيري توزيع توأم مجموعه‌اي از متغيرهاي تصادفي معرفي خواهد شد. اين شبکه از آتاماتاها در محيط‌هايي که پاسخ محيط به مجموعه‌اي از اقدامات انجام‌شده توسط آتاماتا، مستقل از يکديگر نبوده و نوعي وابستگي شرطي ميان اين پاسخ‌ها حاکم باشد، کاربرد دارد. نشان داده شده که اين آتاماتاي جديد قادر است تخميني از توزيع شرطي اقدام‌ها را فرا بگيرد. در ادامه چارچوبی مبتني بر آتاماتاي يادگير توزيع‌شده جديد پيشنهادي، براي حل مسأله يادگيري برخط پارامترهاي یک شبکه بیزی ارائه شده است. اين چارچوب با داده‌ها و شواهد جديد منطبق شده و عمليات به روز رساني پارامترها را انجام مي‌دهد. با بررسي‌هاي رياضي و آزمايش‌هاي عملي روي شبکه‌هاي نمونه، نشان داده‌ايم که اين مدل جديد قادر است با تخميني با دقت برابر با EM، يادگيري پارامترهاي يک شبکه بيزي را انجام دهد. علاوه بر ويژگي افتراقی‌بودن و يادگيري برخط، اين ساختار جديد با شرايطي که داده‌ها ناکامل باشند نيز سازگار است و به دليل استفاده از روابط يادگيري خطي و مبتني بر آتاماتاي يادگير، سربار محاسباتي کمي نيز دارد.
In this paper a new learning automata-based algorithm is proposed for learning of parameters of a Bayesian network. For this purpose, a new team of learning automata which is called eDLA is used. In this paper the structure of Bayesian network is assumed to be fixed. New arriving sample plays role of the random environment and the accuracy of the current parameters generates the random environment reinforcement signal. Linear algorithm is used to update the action selection probability of the automata. Another key issue in Bayesian networks is parameter learning under circumstances that new samples are incomplete. It is shown that new proposed method can be used in this situation. The experiments show that the accuracy of the proposed automata based algorithm is the same as the traditional enumerative methods such as EM. In addition to the online learning characteristics, the proposed algorithm is in accordance with the conditions in which the data are incomplete and due to the use of learning automaton, has a little computational overhead.
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