Abstract
The separation and its applications of binary relative three-weight codes are studied. We first present a certain formula for computing the minimum values of the cardinality of separating coordinate position (CSCP) of some codeword sets for any binary linear code, and then with the above formula, we calculate all the minimum values of the CSCP of binary relative three-weight codes so as to determine their separation. By using the obtained separation of binary relative three-weight codes, some new binary separating codes are constructed. Based on a family of the minimum values of the CSCP of binary relative three-weight codes, we also determine all the minimal codewords and the trellis complexity of binary relative three-weight codes.
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Acknowledgements
The work of Y. Gao is supported in part by the National Key R&D Program of China under grant No. 2017YFB1400700.
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Appendix: A proof of Theorem 4
Appendix: A proof of Theorem 4
We present in this Appendix the proof of Theorem 4.
Proof
It is necessary to get 𝜃2,1 and 𝜃2,2. The computing methods for 𝜃2,1 and 𝜃2,2 are similar. We only take 𝜃2,2 as an example, and our technique is to use Lemma 3 by computing all the possible |𝜃(T,T′)| (|T| = |T′| = 2). Noting that the codewords c2 and c3 in the formula given in Lemma 3 are symmetric, one may list all the possible distributions of independent codewords c1, c2 and c3 and the corresponding |𝜃(T,T′)| as follows.
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1)
c1, c2, c3 ∈ \(\mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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2)
c1, c2 ∈ \(\mathcal {C}_{1}\) and \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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3)
c1, c2 ∈ \(\mathcal {C}_{1}\) and \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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4)
c2, c3 ∈ \(\mathcal {C}_{1}\) and \(c_{1}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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5)
c2, c3 ∈ \(\mathcal {C}_{1}\) and \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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6)
c1 ∈ \(\mathcal {C}_{1}\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {4d_{2}-3d_{1}}{4}\).
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7)
c1 ∈ \(\mathcal {C}_{1}\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{2}-d_{1}}{4}\).
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8)
c1 ∈ \(\mathcal {C}_{1}\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{2}-d_{1}}{4}\).
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9)
c1 ∈ \(\mathcal {C}_{1}\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\) and \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\) and \(c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {4d_{3}-3d_{1}}{4}\).
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10)
c1 ∈ \(\mathcal {C}_{1}\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\) and \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\) and \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {4d_{3}-2d_{2}-d_{1}}{4}\).
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11)
c1 ∈ \(\mathcal {C}_{1}\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\) and \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\) and \(c_{2}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{3}-d_{1}}{4}\).
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12)
c2 ∈ \(\mathcal {C}_{1}\), \(c_{1}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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13)
c2 ∈ \(\mathcal {C}_{1}\), \(c_{1}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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14)
c2 ∈ \(\mathcal {C}_{1}\), \(c_{1}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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15)
c2 ∈ \(\mathcal {C}_{1}\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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16)
c2 ∈ \(\mathcal {C}_{1}\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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17)
c2 ∈ \(\mathcal {C}_{1}\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}+d_{2}-d_{3}}{4}\).
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18)
c2 ∈ \(\mathcal {C}_{1}\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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19)
c1 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}\in \mathcal {C}_{1}\) and \(c_{1}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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20)
c1 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}\in \mathcal {C}_{1}\) and \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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21)
c1 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\) and \(c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{2}-d_{1}}{4}\).
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22)
c1 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\) and \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\) and \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\) and \(c_{1}+c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{2}-d_{1}}{4}\).
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23)
c1 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\) and \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\) and \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\) and \(c_{1}+c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{2}}{4}\).
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24)
c1 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{2}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
-
25)
c1 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{2}}{4}\).
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26)
c2 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{2}-d_{1}}{4}\).
-
27)
c2 ∈ \((\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{2}}{4}\).
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28)
\(c_{1}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {4d_{3}-2d_{2}-d_{1}}{4}\).
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29)
\(c_{1}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {4d_{3}-2d_{2}-d_{1}}{4}\).
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30)
\(c_{1}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {4d_{3}-3d_{2}}{4}\).
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31)
\(c_{1}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{2}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{3}-d_{2}}{4}\).
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32)
\(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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33)
\(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{2}-d_{1}}{4}\).
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34)
\(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{2}}{4}\).
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35)
\(c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{2}}{4}\).
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36)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{2}\in \mathcal {C}_{1}\), and \(c_{1}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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37)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{2}\in \mathcal {C}_{1}\), and \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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38)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}+c_{3}\in \mathcal {C}_{1}\), and \(c_{1}+c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{2}-d_{1}}{4}\).
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39)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), \(c_{1}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{2}}{4}\).
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40)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{2}\in \mathcal {C}_{1}\), and \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\).
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41)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{2}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{2}}{4}\).
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42)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}+c_{3}\in \mathcal {C}_{1}\), and \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{3}-d_{1}}{4}\).
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43)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\), and \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{3}-d_{2}}{ 4}\).
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44)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{2}+c_{3}\in \mathcal {C}_{1}\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{3}-d_{1}}{4}\).
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45)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{2}+c_{3}\in (\mathcal {C}_{2}\backslash \mathcal {C}_{1})\). Then, \(|\theta (T,T^{\prime })|=\frac {2d_{3}-d_{2}}{4}\).
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46)
\(c_{1}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{2}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{1}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), \(c_{2}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\), and \(c_{1}+c_{2}+c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\). Then, \(|\theta (T,T^{\prime })|=\frac {d_{3}}{4}\).
To check each of the above cases, we take case 3) as an example. Since c1, c2 ∈ \(\mathcal {C}_{1}\) and \(c_{3}\in (\mathcal {C}\backslash \mathcal {C}_{2})\) and \(\mathcal {C}_{1}\subset \mathcal {C}_{2}\) are subcodes of \(\mathcal {C}\), one may get \(c_{1}+c_{2}\in \mathcal {C}_{1}\), c1 + c3 ∈ \((\mathcal {C}\backslash \mathcal {C}_{2})\), c2 + c3 ∈ \((\mathcal {C}\backslash \mathcal {C}_{2})\), and c1 + c2 + c3 ∈ \((\mathcal {C}\backslash \mathcal {C}_{2})\). Thus, w(c1) = w(c2) = d1, w(c3) = d3, w(c1 + c2) = d1, w(c1 + c3) = d3, w(c2 + c3) = d3, and w(c1 + c2 + c3) = d3. Then, \(|\theta (T,T^{\prime })|=\frac {d_{1}}{4}\) by using the formula in Lemma 3.
Making use of the above cases, one gets that
The theorem follows by (9). □
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Gao, Y., Liu, Z. & Liu, Y. The separation of binary relative three-weight codes and its applications. Cryptogr. Commun. 11, 979–992 (2019). https://doi.org/10.1007/s12095-018-0339-9
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DOI: https://doi.org/10.1007/s12095-018-0339-9