A note on the ranks of 2?×?2?×?2 and 2?×?2?×?2?×?2 tensors |
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Authors: | Xu Kong |
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Institution: | Department of Mathematical Sciences , Xi'an Jiaotong University , Xi'an , Shaanxi 710049 , China |
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Abstract: | Using rank-1 reduction formula and the vector space spanned by the real rank-1 matrices, we present a different way to show that the maximum possible rank of the 2?×?2?×?2 tensors over the real field is 3. Following, we obtain that the maximum rank of the 2?×?2?×?2?×?2 tensors over the real field is less than or equal to 5 and propose another way to show that the maximum rank of the 2?×?2?×?2?×?2 tensors over the complex field is 4, except one special case. |
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Keywords: | tensor rank vector space uniqueness |
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