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LeanPool.CCDN.Hilbert.PolynomialComparison

Eventual inequalities compare the degree and leading coefficient of Hilbert polynomials.

theorem CCDN.leadingCoeff_nonneg_of_eventual_nat_eval_nonneg (P : Polynomial ℚ) (hP : ∃ (N : ℕ), ∀ n ≥ N, 0 ≤ Polynomial.eval (↑n) P) :

A rational polynomial that is eventually nonnegative on the natural numbers has nonnegative leading coefficient.

theorem CCDN.polynomial_natDegree_le_of_eventual_nat_eval_le (P Q : Polynomial ℚ) (hP : 0 < P.leadingCoeff) (hle : ∃ (N : ℕ), ∀ n ≥ N, Polynomial.eval (↑n) P ≤ Polynomial.eval (↑n) Q) :

If P has positive leading coefficient and P(n) ≤ Q(n) for all large n, then deg P ≤ deg Q.

theorem CCDN.polynomial_leadingCoeff_le_of_eventual_nat_eval_le (P Q : Polynomial ℚ) (hP : 0 < P.leadingCoeff) (hQ : 0 < Q.leadingCoeff) (hd : P.natDegree = Q.natDegree) (hle : ∃ (N : ℕ), ∀ n ≥ N, Polynomial.eval (↑n) P ≤ Polynomial.eval (↑n) Q) :

If P and Q have the same degree and positive leading coefficients and P(n) ≤ Q(n) for all large n, then the leading coefficient of P is at most that of Q.

The filtered Hilbert polynomial of a proper ideal has positive leading coefficient.

Any filtered-dimension inequality between proper polynomial quotients compares their Hilbert dimensions.

When dimensions agree, filtered comparison also compares the leading coefficients, and hence the geometric multiplicities.