11 Let <p> and <q> be a target class files, and <f> be a birthmark
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12 extraction method. Then, <f(p)> and <f(q)> be a extracted birthmarks
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13 which elements are <(e^p_1, e^p_2, ..., e^p_n)> and <(e^q_1, e^q_2,
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18 Let <L> be a number of matched elements of two birthmarks and same
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19 index. Then, the similarity of this method is calculated by
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25 |<f(p) cap f(q)>| / |<f(p)>| |<f(q)>|
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37 Using this comparison method, birthmarks must have name and its
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38 frequency. Therefore, elements of <f(p)> be a set of <(\{name_1,
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39 freq_1\}, \{name_2, freq_2\}, ..., \{name_n, freq_n\})>.
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41 Next, if <f(p)> have name <FOO> and <f(q)> do not have <FOO>, we add
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42 element <\{FOO, 0\}> to f(q). Both birthmarks makes to appearing all
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45 Then, the similarity of <f(p)> and <f(q)>is denoted by
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47 <norm1 = sqrt(freq^p_1 * freq^p_1 + freq^p_2 * freq^p_2 + ... + freq^p_n * freq^p_n)>
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49 <norm2 = sqrt(freq^q_1 * freq^q_1 + freq^q_2 * freq^q_2 + ... + freq^q_n * freq^q_n)>
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51 <product = freq^p_1 * freq^q_1 + freq^p_2 * freq^q_2 + ... + freq^p_n * freq^q_n>
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53 <similarity = product / (norm1 * norm2)>