3.10 Wilson's Theorem and Euler's Theorem
www.whitman.edu › mathematics › higher_math_onlineMar 10, 2011 · 3.10 Wilson's Theorem and Euler's Theorem. The defining characteristic of Un is that every element has a unique multiplicative inverse. It is quite possible for an element of Un to be its own inverse; for example, in U12 , [1]2 = [11]2 = [5]2 = [7]2 = [1]. This stands in contrast to arithmetic in Z or R, where the only solutions to x2 = 1 are ± 1.
A proof of Wilson's Theorem
primes.utm.edu › notes › proofsTo save you some time we present a proof here. Proof. It is easy to check the result when p is 2 or 3, so let us assume p > 3. If p is composite, then its positive divisors are among the integers. and it is clear that gcd ( ( p -1)!, p) > 1, so we can not have ( p -1)! ≡ -1 (mod p ). However if p is prime, then each of the above integers are ...