Description: Lemma for wilth . Here we round out the argument of wilthlem2 with the final step of the induction. The induction argument shows that every subset of 1 ... ( P - 1 ) that is closed under inverse and contains P - 1 multiplies to -u 1 mod P , and clearly 1 ... ( P - 1 ) itself is such a set. Thus, the product of all the elements is -u 1 , and all that is left is to translate the group sum notation (which we used for its unordered summing capabilities) into an ordered sequence to match the definition of the factorial. (Contributed by Mario Carneiro, 24-Jan-2015) (Proof shortened by AV, 27-Jul-2019)
Ref | Expression | ||
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Hypotheses | wilthlem.t | |
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wilthlem.a | |
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Assertion | wilthlem3 | |