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On a special type of permutation rational functions
Let p be a prime and n be a positive integer. We consider rational functions f b ( X ) = X + 1 / ( X p - X + b ) over F p n with Tr ( b ) ≠ 0 . In Hou and Sze (Finite Fields Appl 68, Paper No. 10175, 2020), it is shown that f b ( X ) is not a permutation for p > 3 and n ≥ 5 , while it is for p =...
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Published in: | Applicable algebra in engineering, communication and computing communication and computing, 2024-11, Vol.35 (6), p.821-832 |
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Main Author: | |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites |
Online Access: | Get full text |
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Summary: | Let
p
be a prime and
n
be a positive integer. We consider rational functions
f
b
(
X
)
=
X
+
1
/
(
X
p
-
X
+
b
)
over
F
p
n
with
Tr
(
b
)
≠
0
. In Hou and Sze (Finite Fields Appl 68, Paper No. 10175, 2020), it is shown that
f
b
(
X
)
is not a permutation for
p
>
3
and
n
≥
5
, while it is for
p
=
2
,
3
and
n
≥
1
. It is conjectured that
f
b
(
X
)
is also not a permutation for
p
>
3
and
n
=
3
,
4
, which was recently proved sufficiently large primes in Bartoli and Hou (Finite Fields Appl 76, Paper No. 101904, 2021). In this note, we give a new proof for the fact that
f
b
(
X
)
is not a permutation for
p
>
3
and
n
≥
5
. With this proof, we also show the existence of many elements
b
∈
F
p
n
for which
f
b
(
X
)
is not a permutation for
n
=
3
,
4
. |
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ISSN: | 0938-1279 1432-0622 |
DOI: | 10.1007/s00200-022-00592-1 |