In: Advanced Math
Let F be a finite field. Prove that there exists an integer n≥1, such that n.1_F = 0_F .
Show further that the smallest positive integer with this property is a prime number.
Given data,
Let F be a finite field
Let char(F) = m
Then
,
In particular,
Hence,
=
upto m times
Therefore, the asked n is of the form n = mK,
.
Let char(F) =
If possible suppose that
be not prime
Let
= rs,(a conjugate number where r,s > 1).
So,
.a =
(by
definition of characteristic)
In particular,
=
=>
=
=>
=>
or
(as F is a field, hence it is a integral domain)
char(F) = r <
or char(F) = S <
- a contradiction.
(as
is the least positive integer such that
=
)
Hence, char(F) = p, a prime.