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.