1. )2 ? 2(𝑋 --𝑂 𝐿𝑅 23 𝑂 𝐹𝐵 23 )3 1(? * )2 ? 2(𝑋 ++ 𝑂 𝐿𝑅 23 𝑂 𝐹𝐵 23 )3 1(𝑋 ++ 𝑂 𝐿𝑅 12 𝑂 𝐹𝐵 12 )2 ? 2( ? 𝑂 𝐹𝐵 23 )3, 1( . In table 4, these compositions have been shaded in dark grey to distinguish ? 𝑂 𝐹𝐵 12 )2 ? 2( ? 𝑂 𝐹𝐵 23 )3}, 𝑆 ? 𝑍 References;Communications of the ACM,1983
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