The Convention 1. The data illustrate the article's on, when it comes to the main transaction is said to have converted the transaction form as in table 3.Definition 4. The useful value of X in T, denoted u (X, T), is the total value of the useful elements of X have in dealing T or u (X, T) = ∑i _ (i ∈ X ∧ X ⊆ T) on u (i, T) 〖 〗 [6]Definition 5. The useful value of X, denoted u (X), is the total value of X in all useful transaction T containing X on the DB or u (X) = ∑i _ (T ∈ T ⊆ X ∧ DB) on u (T). 〗 〖 [6]Definition 6. The previous threshold for the minimum useful minutil, set X is called the high useful if the value of X is not less than useful threshold or u (X) ≥ minutil. [6]For example: u ({ab}, T2) = u (a, T2) + u (b, T2) = 4 + 1.9 = 5.9, and u ({ab}) = u ({ab}, T2) + u ({ab}, T4) + u ({ab}, T5) = 5.9 + 9.9 + 13.2 = 34.If minutil = 30 then {ab} is highly useful, in contrast with minutil = 40, then the {ab} is not useful.Definition 7. The useful value of the transaction, the tu T (T), is the total value of the parts are useful in T or tu (T) = ∑i _ (i ∈ T) on u (i, T) 〖 〗 and useful value of DB is the total value of the transaction in useful DB [6]. For example: tu (T3) = u ({a}, T3) + u ({c}, T3) + u ({d}, T3) = 4.4 + 2.2 + 5.5 = 12.1Definition 8. The weight of useful transaction set X, denoted TWU (X), is the total value of all the useful transaction contains X on the DB or the TWU (X) = ∑i _ (T ∈ T ⊆ X ∧ DB) on 〗 〖 tu (T) [6]. For example, TWU ({e}) = tu (T2) + tu (T4) = 17.4 + 24.2 = 41.6Definition 9. ≻ Call is allowed to order the elements of the episode I by TWU. Remaining useful value of X in T, denoted r u (X, T) is a useful value in the element X in T, or is r u (X, T) = ∑i _ (i ∈ T ∧ ∀ x ∈ x ≻ i X) on u (i, T) 〖 〗. [3]For example, ru ({a}, T3) = u ({c}, T3) + u ({d}, T3) = 2.2 + 5.5 = 7.7Definition 10. For the set of elements of I are ranked according to ≻, and set X, the set of elements X extensions are defined as E (X) = {z ∈ z ∧ z I | not ≻ x ∀ x ∈ X} [11]Definition 11. For transaction T and set X, the projection of the X on the T transaction is identified as T_X = {i not | i ∈ T ∧ i ∈ E (X)} [11]For example, For X = {b}, consider allowing the order a b c d ≻ ≻ ≻ ≻ 〖 〗 T1 _ X, then e = ∅, 〖 〗 T2 _ X = {a}Definition 12. For database D and X, the projection of the X on the D was defined as D_X = {T_X not | T ∈ D ∧ T_X ≠ ∅} [11]For example, For X = {c}, consider allowing the order a b c d ≻ ≻ ≻ ≻ e, D_X = {〖 〗 〖 T2, X _ T1 〗 〖 (X), _ T3 T5 〗 〖 〗 _ X _ X} = {{b}, {ab}, {a}, {ab}}Define 13. For a set X, an element z ∈ E (X) and the local utility value of (X, z) is calculated as following lu (X, z) = ∑i _ (T ⊃ (X ∪ {z})) on 〖 [u (X, T) + 〗 ru (X, T)] [11]For example. Let X = {a}, lu (X, c) = (u (X, T2) + ru (X, T2)) + (u (X, T3) + ru (X, T3)) + (u (X, T5) + ru (X, T5)) = 17.4 + 12.1 + 21.6 = 51.1Nature 1. For a set X, z ∈ E (X), if lu (X, z)Definition 14. For a set X and an element z ∈ E (X)), useful value on branch z and X is (X, z) = ∑i _ (T ⊃ (X ∪ {z}))) on 〖 [u (α, T) + u (z, T) + ∑i 〗 _ (i ∈ T ⋀ i ∈ E (α ⋃ {z})) on 〖 u (i, T)] 〗 [11]For example. Let X = {a}, (X, c) = (({a}, T2) + u ({c}, T2) + u ({d}, T2) + u ({e}, T2)) + (({a}, T3) + u ({c}, T3) + u ({d}, T3)) + (({a}, T5) + u ({c}, T5) + u ({f}, T5)) = 15.5 + 12.1 + 12 = 39.6.Nature 2. To set X and z ∈ E (X), if (X, z)Define 15. For the set X, the main element and side elements (Primary, Secondary item) are defined as Primary (X) = {z ∈ z E | not (X) ∧ (X, z) ≥ minutil} and Secondary (X) = {z ∈ z E | not (X) ∧ lu (X, z) ≥ minutil}. [11]For example. Continuing the example in the definition of 13 and 14, if the review minutil = 40 then X = {a} is 1 extra element but not the main element, but with minutil = 30 then X = {a} is the main element is the element.Definition 16. For two transactions, Tb contains the corresponding element {i1, i2, ..., im} and {j1, j2, ..., jn}. TA and Tb are called homogeneous or Ta = Tb if happy the following conditions n = m and ∀ ∈ k [1, n], ik = jk [11]. For example, consider the next example in the definition of 12, then T2 〗 〖 _ (X) and T5 〗 〖 _ X are considered identical because the same results as {a, b}.Definitions 17. For the same transaction for Tr1 Tr2 = ... =. = Trm on D, the trading on mixed with Tm which ∀ i ∈ T_m, u (i, T _ (m)) = ∑i _ (k = 1 ... m) on 〖 〗 u (i, T_k). For example, suppose 〖 〗 _ (X) T2 and T5 〗 〖 _ X 12 is defined in 2 transactions are independent, then the two transactions are changed by 〗 〖 T2 ' _ (X) have useful internal u value ({a}, 〗 〖 T2 ^ ' _ (X)) = u ({a}, 〖 〗 T2 _ (X)) + u ({a} T5 〗 〖, _ (X)) = 4 + 3.6 = 7.6 and u ({b} 〗 〖, T2 ^ ' _ (X)) = u ({b}, 〖 〗 T2 _ (X)) + u ({b} 〖 〗 T5, _ (X)) = 1.9 + 9.6 = 11.5 Define 18. (about the projection incorporates the same transaction mix for) when the projection set X onto D, homogeneous transactions is mixed with a new transaction, cDX. [11]. For example: combined projection mix is expressed specifically in Figure 5 of the example illustrates the algorithm MEFIM.
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