FormalConjectures/ErdosProblems/306.lean

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Explanation legend Lean4 Domain Explanation Language (L4DEL)

L4DEL explanations are a separate layer. They do not change the Lean source. Intuition is explanatory prose; numbered items are a reading path; sources link the wording back to evidence.

L4DEL
Lean4 Domain Explanation Language

Credit: The upstream authors and contributors retain credit for the project and mathematics. lean4-explainer only renders their pinned source and adds the separately disclosed explanation layer.

Project sources: Pinned project documentation, Formal Conjectures paper, arXiv v1

2 declarations, 2 contain sorry, 0 declared as axioms

Erdős Problem 306

References:

Imports (1)
  1. theorem Erdos306.erdos_306 Let $\frac a b\in \mathbb{Q}_{>0}$ with $b$ squarefree sorry line 44 source

    Source documentation

    Let $\frac a b\in \mathbb{Q}_{>0}$ with $b$ squarefree. Are there integers $1 < n_1 < \dots < n_k$, each the product of two distinct primes, such that $\frac{a}{b}=\frac{1}{n_1}+\cdots+\frac{1}{n_k}$?

    depends on sorry what this means

    Statement uses: Iff, True, Rat, LT.lt, OfNat.ofNat, Squarefree, Nat, Rat.den, Exists, Fin, HAdd.hAdd, And, Eq, StrictMono, Membership.mem, Finset, Finset.Icc, Fin.last, ArithmeticFunction, ArithmeticFunction.cardDistinctFactors and 3 more

    Proof uses: sorryAx, Lean.Name, Bool.false, Lean.Name.num, Lean.Name.str, Lean.Name.anonymous

    48 instances, coercions and auxiliary constants left out.

    Tactic trace: 1 steps

    Open to load the checked before-and-after goal states.

    theorem erdos_306 : answer(sorry) ↔ ∀ (q : ℚ), 0 < q → Squarefree q.den →
        ∃ k : ℕ, ∃ (n : Fin (k + 1) → ℕ), n 0 = 1 ∧ StrictMono n ∧
        (∀ i ∈ Finset.Icc 1 (Fin.last k), ω (n i) = 2 ∧ Ω (n i) = 2) ∧
        q = ∑ i ∈ Finset.Icc 1 (Fin.last k), (1 : ℚ) / (n i) := by
    …
  2. theorem Erdos306.erdos_306.variants.integer_three_primes Every positive integer can be expressed as an Egyptian fraction where each denominator is the product of three distinct primes sorry line 55 source

    Source documentation

    Every positive integer can be expressed as an Egyptian fraction where each denominator is the product of three distinct primes.

    depends on sorry what this means

    Statement uses: Nat, LT.lt, OfNat.ofNat, Exists, And, GT.gt, Fin, HAdd.hAdd, Eq, Fin.mk, Membership.mem, Finset, Finset.Icc, Fin.last, ArithmeticFunction, ArithmeticFunction.cardDistinctFactors, ArithmeticFunction.cardFactors, Rat, Finset.sum, HDiv.hDiv

    Proof uses: sorryAx, Lean.Name, Bool.false, Lean.Name.num, Lean.Name.str, Lean.Name.anonymous

    48 instances, coercions and auxiliary constants left out.

    Tactic trace: 3 steps

    Open to load the checked before-and-after goal states.

    theorem erdos_306.variants.integer_three_primes (m : ℕ) (h : 0 < m) :
        ∃ k > (0 : ℕ), ∃ (n : Fin (k + 1) → ℕ), n 0 = 1 ∧
        ∀ i, (hik : i < k) → n ⟨i, by omega⟩ < n ⟨(i + 1), by omega⟩ ∧
        (∀ i ∈ Finset.Icc 1 (Fin.last k), ω (n i) = 3 ∧ Ω (n i) = 3) ∧
        m = ∑ i ∈ Finset.Icc 1 (Fin.last k), (1 : ℚ) / (n i) := by
    …