Kummer's Criterion and Regular Primes in Lean

9.4. Escaping every finite set🔗

Theorem9.4.1
Statement uses 2
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Theorem 9.2.1
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used by 1L∃∀N

Finite-set escape. For every finite set S\subset\mathbb{N}, there is a prime p\notin S such that p is not regular.

Theorem 9.3.2 Theorem 9.2.1

Lean code for Theorem9.4.11 theorem
  • theoremdefined in BernoulliRegular/IrregularPrimes/Infinitude.lean
    complete
    theorem BernoulliRegular.exists_not_isRegularPrime_not_mem_carlitz
      (S : Finset ) :  p,  (_ : Nat.Prime p), ¬IsRegularPrime p  p  S
    theorem BernoulliRegular.exists_not_isRegularPrime_not_mem_carlitz
      (S : Finset ) :
       p,
         (_ : Nat.Prime p),
          ¬IsRegularPrime p  p  S
    Carlitz finite-set contradiction. 
Proof for Theorem 9.4.1
uses 0

Apply Theorem 9.3.2 to S, obtaining a prime p\notin S and a positive even M with p\mid\operatorname{num}\left(\frac{B_M}{M}\right). The same theorem gives p\ne 2. Therefore the Carlitz divisor criterion Theorem 9.2.1 applies and proves that p is not regular.