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On the number of irreducible linear transformation shift registers

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Abstract

We deal with the problem of counting the number of irreducible linear transformation shift registers (TSRs) over a finite field. In a recent paper, Ram reduced this problem to calculate the cardinality of some set of irreducible polynomials and got explicit formulae for the number of irreducible TSRs of order two. We find a bijection between Ram’s set to another set of irreducible polynomials which is easier to count, and then give a conjecture about the number of irreducible TSRs of any order. We also get explicit formulae for the number of irreducible TSRs of order three.

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Acknowledgments

The authors thank the referees for pointing out the recent Reference [2] in which Cohen et al. proved Conjecture 2 for the odd characteristic case. In an earlier version, we gave a self-contained proof for the explicit number of irreducible polynomials of degree 3 in Section 3. We thank a referee for introducing us the Reference [17]. Applying the results about value sets, Section 3 is considerably shortened. This work was supported by the National Natural Science Foundation of China under Grants 61379139, 61502483 and 11526215, and the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant XDA06010701.

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Correspondence to Yupeng Jiang.

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Communicated by D. Panario.

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Jiang, Y., Yang, J. On the number of irreducible linear transformation shift registers. Des. Codes Cryptogr. 83, 445–454 (2017). https://doi.org/10.1007/s10623-016-0240-5

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