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Top1. Introduction
Nowadays, machines have many applications in different contexts with the ability to recognize pattern. The examples of these machines are those which capable of reading alphabetical symbols. In fact, these provide economical alternatives to user directory method. These programs save time and cost and cause less errors. One of these machines which capable of learning is ANNs (Demuth & Beale, 2002). The ANNs play an important role in pattern recognition applications. The recognition systems are used in many contexts which had different natures. One of these contexts is letters recognition. During last decades, considerable developments are achieved in this feature such as automatic reading of postal address, bank checks and so on. Letters recognition is one of the issues which don't have any particular rule or algorithm and it can be used different methods to design its systems and each one has its own special advantages and disadvantages. Letters recognition is a process which must be performed several repetitions in it. This repetition process must be occurred to get desirable results (Rashnodi, Sajedi, & Abadeh, 2011; Meisels, Kandel, & Gecht, 1989).
Letters recognition is one of the fields of pattern recognition, which has been the subject of considerable research (Ahangar & Ahangar, 2009). Many reports are published about word recognition in different languages such as Chinese (Yeung, 1994), Japanese (Yamada, Kami, Temma, & Tsukumo, 1989), English (Morasso, 1989; Smith, Baurgoin, Sims, & Voorhees, 1994), Arabic (Almualim & Yamaguchi, 1987; Abuhaiba, Mahmoud, & Green, 1994; Gharehchopogh & Ahmadzadeh, 2012) and Farsi (Ahangar & Ahangar, 2009; Gharehchopogh & Ahmadzadeh, 2012). But yet, recognizing Kurdish letters due to the some occurred issues are in recognizing these letters aren't performed. It is a very complicated problem which includes many changes in writing styles, size and different sides of different languages' characters. Because, writing characters as matrix in different sizes and make them into the particular form is a difficult task. These changes can be repeated infinitely (Gharehchopogh & Ahmadzadeh, 2012; Gharehchopogh, 2011) and ANNs had proper efficiency to solve this problem. The ANNs is adopted as a new technology in computer science which supposed to simulate human brain neurons behavior. It is mostly used in many cases in the recent years such as ANNs capabilities in recognition, estimation and prediction (Gharehchopogh, 2011).