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monic.dvd_of_fraction_map_dvd_fraction_map [is_integrally_closed R] {p q : R[X]} (hp : p.monic ) (hq : q.monic) (h : q.map (algebra_map R K) ∣ p.map (algebra_map R K)) : q ∣ p
begin obtain ⟨r, hr⟩ := h, obtain ⟨d', hr'⟩ := is_integrally_closed.eq_map_mul_C_of_dvd K hp (dvd_of_mul_left_eq _ hr.symm), rw [monic.leading_coeff, C_1, mul_one] at hr', rw [← hr', ← polynomial.map_mul] at hr, exact dvd_of_mul_right_eq _ (polynomial.map_injective _ (is_fraction_ring.injective R K) hr.symm),...
theorem
polynomial.monic.dvd_of_fraction_map_dvd_fraction_map
ring_theory.polynomial
src/ring_theory/polynomial/gauss_lemma.lean
[ "field_theory.splitting_field.construction", "ring_theory.int.basic", "ring_theory.localization.integral", "ring_theory.integrally_closed" ]
[ "algebra_map", "is_fraction_ring.injective", "is_integrally_closed", "is_integrally_closed.eq_map_mul_C_of_dvd", "mul_one", "polynomial.map_injective", "polynomial.map_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
monic.dvd_iff_fraction_map_dvd_fraction_map [is_integrally_closed R] {p q : R[X]} (hp : p.monic ) (hq : q.monic) : q.map (algebra_map R K) ∣ p.map (algebra_map R K) ↔ q ∣ p
⟨λ h, hp.dvd_of_fraction_map_dvd_fraction_map hq h, λ ⟨a,b⟩, ⟨a.map (algebra_map R K), b.symm ▸ polynomial.map_mul (algebra_map R K)⟩⟩
theorem
polynomial.monic.dvd_iff_fraction_map_dvd_fraction_map
ring_theory.polynomial
src/ring_theory/polynomial/gauss_lemma.lean
[ "field_theory.splitting_field.construction", "ring_theory.int.basic", "ring_theory.localization.integral", "ring_theory.integrally_closed" ]
[ "algebra_map", "is_integrally_closed", "polynomial.map_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_unit_or_eq_zero_of_is_unit_integer_normalization_prim_part {p : K[X]} (h0 : p ≠ 0) (h : is_unit (integer_normalization R⁰ p).prim_part) : is_unit p
begin rcases is_unit_iff.1 h with ⟨_, ⟨u, rfl⟩, hu⟩, obtain ⟨⟨c, c0⟩, hc⟩ := integer_normalization_map_to_map R⁰ p, rw [subtype.coe_mk, algebra.smul_def, algebra_map_apply] at hc, apply is_unit_of_mul_is_unit_right, rw [← hc, (integer_normalization R⁰ p).eq_C_content_mul_prim_part, ← hu, ← ring_hom.map_mu...
lemma
polynomial.is_unit_or_eq_zero_of_is_unit_integer_normalization_prim_part
ring_theory.polynomial
src/ring_theory/polynomial/gauss_lemma.lean
[ "field_theory.splitting_field.construction", "ring_theory.int.basic", "ring_theory.localization.integral", "ring_theory.integrally_closed" ]
[ "algebra.smul_def", "algebra_map", "algebra_map_apply", "con", "is_fraction_ring.injective", "is_fraction_ring.integer_normalization_eq_zero_iff", "is_unit", "is_unit_of_mul_is_unit_right", "mul_eq_zero", "ring_hom.map_mul", "subtype.coe_mk", "units.ne_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_primitive.irreducible_iff_irreducible_map_fraction_map {p : R[X]} (hp : p.is_primitive) : irreducible p ↔ irreducible (p.map (algebra_map R K))
begin refine ⟨λ hi, ⟨λ h, hi.not_unit (hp.is_unit_iff_is_unit_map.2 h), λ a b hab, _⟩, hp.irreducible_of_irreducible_map_of_injective (is_fraction_ring.injective _ _)⟩, obtain ⟨⟨c, c0⟩, hc⟩ := integer_normalization_map_to_map R⁰ a, obtain ⟨⟨d, d0⟩, hd⟩ := integer_normalization_map_to_map R⁰ b, rw [algebra.s...
theorem
polynomial.is_primitive.irreducible_iff_irreducible_map_fraction_map
ring_theory.polynomial
src/ring_theory/polynomial/gauss_lemma.lean
[ "field_theory.splitting_field.construction", "ring_theory.int.basic", "ring_theory.localization.integral", "ring_theory.integrally_closed" ]
[ "algebra.smul_def", "algebra_map", "algebra_map_apply", "associated", "con", "dvd_dvd_iff_associated", "irreducible", "is_fraction_ring.injective", "is_unit_of_mul_is_unit_right", "mem_non_zero_divisors_iff_ne_zero", "mul_assoc", "mul_comm", "mul_eq_zero", "mul_left_cancel₀", "mul_ne_zer...
**Gauss's Lemma** for GCD domains states that a primitive polynomial is irreducible iff it is irreducible in the fraction field.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_primitive.dvd_of_fraction_map_dvd_fraction_map {p q : R[X]} (hp : p.is_primitive) (hq : q.is_primitive) (h_dvd : p.map (algebra_map R K) ∣ q.map (algebra_map R K)) : p ∣ q
begin rcases h_dvd with ⟨r, hr⟩, obtain ⟨⟨s, s0⟩, hs⟩ := integer_normalization_map_to_map R⁰ r, rw [subtype.coe_mk, algebra.smul_def, algebra_map_apply] at hs, have h : p ∣ q * C s, { use (integer_normalization R⁰ r), apply map_injective (algebra_map R K) (is_fraction_ring.injective _ _), rw [polynomi...
lemma
polynomial.is_primitive.dvd_of_fraction_map_dvd_fraction_map
ring_theory.polynomial
src/ring_theory/polynomial/gauss_lemma.lean
[ "field_theory.splitting_field.construction", "ring_theory.int.basic", "ring_theory.localization.integral", "ring_theory.integrally_closed" ]
[ "algebra.smul_def", "algebra_map", "algebra_map_apply", "associated.dvd_iff_dvd_right", "is_fraction_ring.injective", "mem_non_zero_divisors_iff_ne_zero", "mul_assoc", "mul_comm", "mul_ne_zero", "polynomial.map_mul", "subtype.coe_mk" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_primitive.dvd_iff_fraction_map_dvd_fraction_map {p q : R[X]} (hp : p.is_primitive) (hq : q.is_primitive) : (p ∣ q) ↔ (p.map (algebra_map R K) ∣ q.map (algebra_map R K))
⟨λ ⟨a,b⟩, ⟨a.map (algebra_map R K), b.symm ▸ polynomial.map_mul (algebra_map R K)⟩, λ h, hp.dvd_of_fraction_map_dvd_fraction_map hq h⟩
lemma
polynomial.is_primitive.dvd_iff_fraction_map_dvd_fraction_map
ring_theory.polynomial
src/ring_theory/polynomial/gauss_lemma.lean
[ "field_theory.splitting_field.construction", "ring_theory.int.basic", "ring_theory.localization.integral", "ring_theory.integrally_closed" ]
[ "algebra_map", "polynomial.map_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_primitive.int.irreducible_iff_irreducible_map_cast {p : ℤ[X]} (hp : p.is_primitive) : irreducible p ↔ irreducible (p.map (int.cast_ring_hom ℚ))
hp.irreducible_iff_irreducible_map_fraction_map
theorem
polynomial.is_primitive.int.irreducible_iff_irreducible_map_cast
ring_theory.polynomial
src/ring_theory/polynomial/gauss_lemma.lean
[ "field_theory.splitting_field.construction", "ring_theory.int.basic", "ring_theory.localization.integral", "ring_theory.integrally_closed" ]
[ "int.cast_ring_hom", "irreducible" ]
**Gauss's Lemma** for `ℤ` states that a primitive integer polynomial is irreducible iff it is irreducible over `ℚ`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_primitive.int.dvd_iff_map_cast_dvd_map_cast (p q : ℤ[X]) (hp : p.is_primitive) (hq : q.is_primitive) : (p ∣ q) ↔ (p.map (int.cast_ring_hom ℚ) ∣ q.map (int.cast_ring_hom ℚ))
hp.dvd_iff_fraction_map_dvd_fraction_map ℚ hq
lemma
polynomial.is_primitive.int.dvd_iff_map_cast_dvd_map_cast
ring_theory.polynomial
src/ring_theory/polynomial/gauss_lemma.lean
[ "field_theory.splitting_field.construction", "ring_theory.int.basic", "ring_theory.localization.integral", "ring_theory.integrally_closed" ]
[ "int.cast_ring_hom" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv (R : Type*) [semiring R] : R[X]ᵐᵒᵖ ≃+* Rᵐᵒᵖ[X]
((to_finsupp_iso R).op.trans add_monoid_algebra.op_ring_equiv).trans (to_finsupp_iso _).symm
def
polynomial.op_ring_equiv
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[ "add_monoid_algebra.op_ring_equiv", "semiring" ]
Ring isomorphism between `R[X]ᵐᵒᵖ` and `Rᵐᵒᵖ[X]` sending each coefficient of a polynomial to the corresponding element of the opposite ring.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv_op_monomial (n : ℕ) (r : R) : op_ring_equiv R (op (monomial n r : R[X])) = monomial n (op r)
by simp only [op_ring_equiv, ring_equiv.trans_apply, ring_equiv.op_apply_apply, ring_equiv.to_add_equiv_eq_coe, add_equiv.mul_op_apply, add_equiv.to_fun_eq_coe, add_equiv.coe_trans, op_add_equiv_apply, ring_equiv.coe_to_add_equiv, op_add_equiv_symm_apply, function.comp_app, unop_op, to_finsupp_iso_apply, to...
lemma
polynomial.op_ring_equiv_op_monomial
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[ "add_monoid_algebra.op_ring_equiv_single", "ring_equiv.coe_to_add_equiv", "ring_equiv.to_add_equiv_eq_coe", "ring_equiv.trans_apply" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv_op_C (a : R) : op_ring_equiv R (op (C a)) = C (op a)
op_ring_equiv_op_monomial 0 a
lemma
polynomial.op_ring_equiv_op_C
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv_op_X : op_ring_equiv R (op (X : R[X])) = X
op_ring_equiv_op_monomial 1 1
lemma
polynomial.op_ring_equiv_op_X
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv_op_C_mul_X_pow (r : R) (n : ℕ) : op_ring_equiv R (op (C r * X ^ n : R[X])) = C (op r) * X ^ n
by simp only [X_pow_mul, op_mul, op_pow, map_mul, map_pow, op_ring_equiv_op_X, op_ring_equiv_op_C]
lemma
polynomial.op_ring_equiv_op_C_mul_X_pow
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[ "map_mul", "map_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv_symm_monomial (n : ℕ) (r : Rᵐᵒᵖ) : (op_ring_equiv R).symm (monomial n r) = op (monomial n (unop r))
(op_ring_equiv R).injective (by simp)
lemma
polynomial.op_ring_equiv_symm_monomial
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv_symm_C (a : Rᵐᵒᵖ) : (op_ring_equiv R).symm (C a) = op (C (unop a))
op_ring_equiv_symm_monomial 0 a
lemma
polynomial.op_ring_equiv_symm_C
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv_symm_X : (op_ring_equiv R).symm (X : Rᵐᵒᵖ[X]) = op X
op_ring_equiv_symm_monomial 1 1
lemma
polynomial.op_ring_equiv_symm_X
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
op_ring_equiv_symm_C_mul_X_pow (r : Rᵐᵒᵖ) (n : ℕ) : (op_ring_equiv R).symm (C r * X ^ n : Rᵐᵒᵖ[X]) = op (C (unop r) * X ^ n)
by rw [C_mul_X_pow_eq_monomial, op_ring_equiv_symm_monomial, ← C_mul_X_pow_eq_monomial]
lemma
polynomial.op_ring_equiv_symm_C_mul_X_pow
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_op_ring_equiv (p : R[X]ᵐᵒᵖ) (n : ℕ) : (op_ring_equiv R p).coeff n = op ((unop p).coeff n)
begin induction p using mul_opposite.rec, cases p, refl end
lemma
polynomial.coeff_op_ring_equiv
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[ "mul_opposite.rec" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
support_op_ring_equiv (p : R[X]ᵐᵒᵖ) : (op_ring_equiv R p).support = (unop p).support
begin induction p using mul_opposite.rec, cases p, exact finsupp.support_map_range_of_injective _ _ op_injective end
lemma
polynomial.support_op_ring_equiv
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[ "finsupp.support_map_range_of_injective", "mul_opposite.rec" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nat_degree_op_ring_equiv (p : R[X]ᵐᵒᵖ) : (op_ring_equiv R p).nat_degree = (unop p).nat_degree
begin by_cases p0 : p = 0, { simp only [p0, _root_.map_zero, nat_degree_zero, unop_zero] }, { simp only [p0, nat_degree_eq_support_max', ne.def, add_equiv_class.map_eq_zero_iff, not_false_iff, support_op_ring_equiv, unop_eq_zero_iff] } end
lemma
polynomial.nat_degree_op_ring_equiv
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
leading_coeff_op_ring_equiv (p : R[X]ᵐᵒᵖ) : (op_ring_equiv R p).leading_coeff = op (unop p).leading_coeff
by rw [leading_coeff, coeff_op_ring_equiv, nat_degree_op_ring_equiv, leading_coeff]
lemma
polynomial.leading_coeff_op_ring_equiv
ring_theory.polynomial
src/ring_theory/polynomial/opposites.lean
[ "data.polynomial.degree.definitions" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer : ℕ → S[X]
| 0 := 1 | (n+1) := X * (pochhammer n).comp (X + 1)
def
pochhammer
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[]
`pochhammer S n` is the polynomial `X * (X+1) * ... * (X + n - 1)`, with coefficients in the semiring `S`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_zero : pochhammer S 0 = 1
rfl
lemma
pochhammer_zero
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "pochhammer" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_one : pochhammer S 1 = X
by simp [pochhammer]
lemma
pochhammer_one
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "pochhammer" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_succ_left (n : ℕ) : pochhammer S (n+1) = X * (pochhammer S n).comp (X+1)
by rw pochhammer
lemma
pochhammer_succ_left
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "pochhammer" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_map (f : S →+* T) (n : ℕ) : (pochhammer S n).map f = pochhammer T n
begin induction n with n ih, { simp, }, { simp [ih, pochhammer_succ_left, map_comp], }, end
lemma
pochhammer_map
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "ih", "map_comp", "pochhammer", "pochhammer_succ_left" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_eval_cast (n k : ℕ) : ((pochhammer ℕ n).eval k : S) = (pochhammer S n).eval k
begin rw [←pochhammer_map (algebra_map ℕ S), eval_map, ←eq_nat_cast (algebra_map ℕ S), eval₂_at_nat_cast, nat.cast_id, eq_nat_cast], end
lemma
pochhammer_eval_cast
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "algebra_map", "eq_nat_cast", "nat.cast_id", "pochhammer" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_eval_zero {n : ℕ} : (pochhammer S n).eval 0 = if n = 0 then 1 else 0
begin cases n, { simp, }, { simp [X_mul, nat.succ_ne_zero, pochhammer_succ_left], } end
lemma
pochhammer_eval_zero
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "pochhammer", "pochhammer_succ_left" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_zero_eval_zero : (pochhammer S 0).eval 0 = 1
by simp
lemma
pochhammer_zero_eval_zero
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "pochhammer" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_ne_zero_eval_zero {n : ℕ} (h : n ≠ 0) : (pochhammer S n).eval 0 = 0
by simp [pochhammer_eval_zero, h]
lemma
pochhammer_ne_zero_eval_zero
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "pochhammer", "pochhammer_eval_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_succ_right (n : ℕ) : pochhammer S (n+1) = pochhammer S n * (X + n)
begin suffices h : pochhammer ℕ (n+1) = pochhammer ℕ n * (X + n), { apply_fun polynomial.map (algebra_map ℕ S) at h, simpa only [pochhammer_map, polynomial.map_mul, polynomial.map_add, map_X, polynomial.map_nat_cast] using h }, induction n with n ih, { simp, }, { conv_lhs { rw [pochhamme...
lemma
pochhammer_succ_right
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "algebra_map", "ih", "nat.cast_succ", "pochhammer", "pochhammer_map", "pochhammer_succ_left", "polynomial.map", "polynomial.map_add", "polynomial.map_mul", "polynomial.map_nat_cast" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_succ_eval {S : Type*} [semiring S] (n : ℕ) (k : S) : (pochhammer S (n + 1)).eval k = (pochhammer S n).eval k * (k + n)
by rw [pochhammer_succ_right, mul_add, eval_add, eval_mul_X, ← nat.cast_comm, ← C_eq_nat_cast, eval_C_mul, nat.cast_comm, ← mul_add]
lemma
pochhammer_succ_eval
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "nat.cast_comm", "pochhammer", "pochhammer_succ_right", "semiring" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_succ_comp_X_add_one (n : ℕ) : (pochhammer S (n + 1)).comp (X + 1) = pochhammer S (n + 1) + (n + 1) • (pochhammer S n).comp (X + 1)
begin suffices : (pochhammer ℕ (n + 1)).comp (X + 1) = pochhammer ℕ (n + 1) + (n + 1) * (pochhammer ℕ n).comp (X + 1), { simpa [map_comp] using congr_arg (polynomial.map (nat.cast_ring_hom S)) this }, nth_rewrite 1 pochhammer_succ_left, rw [← add_mul, pochhammer_succ_right ℕ n, mul_comp, mul_comm,...
lemma
pochhammer_succ_comp_X_add_one
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "map_comp", "mul_comm", "nat.cast_ring_hom", "pochhammer", "pochhammer_succ_left", "pochhammer_succ_right", "polynomial.map" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial.mul_X_add_nat_cast_comp {p q : S[X]} {n : ℕ} : (p * (X + n)).comp q = (p.comp q) * (q + n)
by rw [mul_add, add_comp, mul_X_comp, ←nat.cast_comm, nat_cast_mul_comp, nat.cast_comm, mul_add]
lemma
polynomial.mul_X_add_nat_cast_comp
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "nat.cast_comm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_mul (n m : ℕ) : pochhammer S n * (pochhammer S m).comp (X + n) = pochhammer S (n + m)
begin induction m with m ih, { simp, }, { rw [pochhammer_succ_right, polynomial.mul_X_add_nat_cast_comp, ←mul_assoc, ih, nat.succ_eq_add_one, ←add_assoc, pochhammer_succ_right, nat.cast_add, add_assoc], } end
lemma
pochhammer_mul
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "ih", "nat.cast_add", "pochhammer", "pochhammer_succ_right", "polynomial.mul_X_add_nat_cast_comp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_nat_eq_asc_factorial (n : ℕ) : ∀ k, (pochhammer ℕ k).eval (n + 1) = n.asc_factorial k
| 0 := by erw [eval_one]; refl | (t + 1) := begin rw [pochhammer_succ_right, eval_mul, pochhammer_nat_eq_asc_factorial t], suffices : n.asc_factorial t * (n + 1 + t) = n.asc_factorial (t + 1), by simpa, rw [nat.asc_factorial_succ, add_right_comm, mul_comm] end
lemma
pochhammer_nat_eq_asc_factorial
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "mul_comm", "nat.asc_factorial_succ", "pochhammer", "pochhammer_succ_right" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_nat_eq_desc_factorial (a b : ℕ) : (pochhammer ℕ b).eval a = (a + b - 1).desc_factorial b
begin cases b, { rw [nat.desc_factorial_zero, pochhammer_zero, polynomial.eval_one] }, rw [nat.add_succ, nat.succ_sub_succ, tsub_zero], cases a, { rw [pochhammer_ne_zero_eval_zero _ b.succ_ne_zero, zero_add, nat.desc_factorial_of_lt b.lt_succ_self] }, { rw [nat.succ_add, ←nat.add_succ, nat.add_desc_fact...
lemma
pochhammer_nat_eq_desc_factorial
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "nat.add_desc_factorial_eq_asc_factorial", "nat.desc_factorial_zero", "pochhammer", "pochhammer_nat_eq_asc_factorial", "pochhammer_ne_zero_eval_zero", "pochhammer_zero", "polynomial.eval_one", "tsub_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_pos (n : ℕ) (s : S) (h : 0 < s) : 0 < (pochhammer S n).eval s
begin induction n with n ih, { simp only [nat.nat_zero_eq_zero, pochhammer_zero, eval_one], exact zero_lt_one, }, { rw [pochhammer_succ_right, mul_add, eval_add, ←nat.cast_comm, eval_nat_cast_mul, eval_mul_X, nat.cast_comm, ←mul_add], exact mul_pos ih (lt_of_lt_of_le h ((le_add_iff_nonneg_right _)...
lemma
pochhammer_pos
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "ih", "nat.cast_comm", "nat.cast_nonneg", "pochhammer", "pochhammer_succ_right", "pochhammer_zero", "zero_lt_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_eval_one (S : Type*) [semiring S] (n : ℕ) : (pochhammer S n).eval (1 : S) = (n! : S)
by rw_mod_cast [pochhammer_nat_eq_asc_factorial, nat.zero_asc_factorial]
lemma
pochhammer_eval_one
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "nat.zero_asc_factorial", "pochhammer", "pochhammer_nat_eq_asc_factorial", "semiring" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
factorial_mul_pochhammer (S : Type*) [semiring S] (r n : ℕ) : (r! : S) * (pochhammer S n).eval (r + 1) = (r + n)!
by rw_mod_cast [pochhammer_nat_eq_asc_factorial, nat.factorial_mul_asc_factorial]
lemma
factorial_mul_pochhammer
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "nat.factorial_mul_asc_factorial", "pochhammer", "pochhammer_nat_eq_asc_factorial", "semiring" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_nat_eval_succ (r : ℕ) : ∀ n : ℕ, n * (pochhammer ℕ r).eval (n + 1) = (n + r) * (pochhammer ℕ r).eval n
| 0 := begin by_cases h : r = 0, { simp only [h, zero_mul, zero_add], }, { simp only [pochhammer_eval_zero, zero_mul, if_neg h, mul_zero], } end | (k + 1) := by simp only [pochhammer_nat_eq_asc_factorial, nat.succ_asc_factorial, add_right_comm]
lemma
pochhammer_nat_eval_succ
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "mul_zero", "nat.succ_asc_factorial", "pochhammer", "pochhammer_eval_zero", "pochhammer_nat_eq_asc_factorial", "zero_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pochhammer_eval_succ (r n : ℕ) : (n : S) * (pochhammer S r).eval (n + 1 : S) = (n + r) * (pochhammer S r).eval n
by exact_mod_cast congr_arg nat.cast (pochhammer_nat_eval_succ r n)
lemma
pochhammer_eval_succ
ring_theory.polynomial
src/ring_theory/polynomial/pochhammer.lean
[ "tactic.abel", "data.polynomial.eval" ]
[ "nat.cast", "pochhammer", "pochhammer_nat_eval_succ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quotient_span_X_sub_C_alg_equiv (x : R) : (R[X] ⧸ ideal.span ({X - C x} : set R[X])) ≃ₐ[R] R
(ideal.quotient_equiv_alg_of_eq R (by exact ker_eval_ring_hom x : ring_hom.ker (aeval x).to_ring_hom = _)).symm.trans $ ideal.quotient_ker_alg_equiv_of_right_inverse $ λ _, eval_C
def
polynomial.quotient_span_X_sub_C_alg_equiv
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal.quotient_equiv_alg_of_eq", "ideal.quotient_ker_alg_equiv_of_right_inverse", "ideal.span", "ring_hom.ker" ]
For a commutative ring $R$, evaluating a polynomial at an element $x \in R$ induces an isomorphism of $R$-algebras $R[X] / \langle X - x \rangle \cong R$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quotient_span_X_sub_C_alg_equiv_mk (x : R) (p : R[X]) : quotient_span_X_sub_C_alg_equiv x (ideal.quotient.mk _ p) = p.eval x
rfl
lemma
polynomial.quotient_span_X_sub_C_alg_equiv_mk
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal.quotient.mk" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quotient_span_X_sub_C_alg_equiv_symm_apply (x : R) (y : R) : (quotient_span_X_sub_C_alg_equiv x).symm y = algebra_map R _ y
rfl
lemma
polynomial.quotient_span_X_sub_C_alg_equiv_symm_apply
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "algebra_map" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quotient_span_C_X_sub_C_alg_equiv (x y : R) : (R[X] ⧸ (ideal.span {C x, X - C y} : ideal R[X])) ≃ₐ[R] R ⧸ (ideal.span {x} : ideal R)
(ideal.quotient_equiv_alg_of_eq R $ by rw [ideal.span_insert, sup_comm]).trans $ (double_quot.quot_quot_equiv_quot_supₐ R _ _).symm.trans $ (ideal.quotient_equiv_alg _ _ (quotient_span_X_sub_C_alg_equiv y) rfl).trans $ ideal.quotient_equiv_alg_of_eq R $ by { simp only [ideal.map_span, set.image_sing...
def
polynomial.quotient_span_C_X_sub_C_alg_equiv
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "double_quot.quot_quot_equiv_quot_supₐ", "ideal", "ideal.map_span", "ideal.quotient_equiv_alg", "ideal.quotient_equiv_alg_of_eq", "ideal.span", "ideal.span_insert", "set.image_singleton", "sup_comm" ]
For a commutative ring $R$, evaluating a polynomial at an element $y \in R$ induces an isomorphism of $R$-algebras $R[X] / \langle x, X - y \rangle \cong R / \langle x \rangle$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quotient_map_C_eq_zero {I : ideal R} : ∀ a ∈ I, ((quotient.mk (map (C : R →+* R[X]) I : ideal R[X])).comp C) a = 0
begin intros a ha, rw [ring_hom.comp_apply, quotient.eq_zero_iff_mem], exact mem_map_of_mem _ ha, end
lemma
ideal.quotient_map_C_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "ring_hom.comp_apply" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eval₂_C_mk_eq_zero {I : ideal R} : ∀ f ∈ (map (C : R →+* R[X]) I : ideal R[X]), eval₂_ring_hom (C.comp (quotient.mk I)) X f = 0
begin intros a ha, rw ← sum_monomial_eq a, dsimp, rw eval₂_sum, refine finset.sum_eq_zero (λ n hn, _), dsimp, rw eval₂_monomial (C.comp (quotient.mk I)) X, refine mul_eq_zero_of_left (polynomial.ext (λ m, _)) (X ^ n), erw coeff_C, by_cases h : m = 0, { simpa [h] using quotient.eq_zero_iff_mem.2 ((...
lemma
ideal.eval₂_C_mk_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "mul_eq_zero_of_left", "polynomial.ext" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial_quotient_equiv_quotient_polynomial (I : ideal R) : (R ⧸ I)[X] ≃+* R[X] ⧸ (map C I : ideal R[X])
{ to_fun := eval₂_ring_hom (quotient.lift I ((quotient.mk (map C I : ideal R[X])).comp C) quotient_map_C_eq_zero) ((quotient.mk (map C I : ideal R[X]) X)), inv_fun := quotient.lift (map C I : ideal R[X]) (eval₂_ring_hom (C.comp (quotient.mk I)) X) eval₂_C_mk_eq_zero, map_mul' := λ f g, by simp only [coe...
def
ideal.polynomial_quotient_equiv_quotient_polynomial
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "inv_fun", "polynomial.induction_on'", "quotient.lift_mk", "ring_hom.coe_comp", "ring_hom.map_add", "ring_hom.map_mul", "ring_hom.map_pow", "submodule.quotient.quot_mk_eq_mk" ]
If `I` is an ideal of `R`, then the ring polynomials over the quotient ring `I.quotient` is isomorphic to the quotient of `R[X]` by the ideal `map C I`, where `map C I` contains exactly the polynomials whose coefficients all lie in `I`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial_quotient_equiv_quotient_polynomial_symm_mk (I : ideal R) (f : R[X]) : I.polynomial_quotient_equiv_quotient_polynomial.symm (quotient.mk _ f) = f.map (quotient.mk I)
by rw [polynomial_quotient_equiv_quotient_polynomial, ring_equiv.symm_mk, ring_equiv.coe_mk, ideal.quotient.lift_mk, coe_eval₂_ring_hom, eval₂_eq_eval_map, ←polynomial.map_map, ←eval₂_eq_eval_map, polynomial.eval₂_C_X]
lemma
ideal.polynomial_quotient_equiv_quotient_polynomial_symm_mk
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "ideal.quotient.lift_mk", "polynomial.eval₂_C_X", "ring_equiv.coe_mk", "ring_equiv.symm_mk" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial_quotient_equiv_quotient_polynomial_map_mk (I : ideal R) (f : R[X]) : I.polynomial_quotient_equiv_quotient_polynomial (f.map I^.quotient.mk) = quotient.mk _ f
begin apply (polynomial_quotient_equiv_quotient_polynomial I).symm.injective, rw [ring_equiv.symm_apply_apply, polynomial_quotient_equiv_quotient_polynomial_symm_mk], end
lemma
ideal.polynomial_quotient_equiv_quotient_polynomial_map_mk
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "ring_equiv.symm_apply_apply" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_domain_map_C_quotient {P : ideal R} (H : is_prime P) : is_domain (R[X] ⧸ (map (C : R →+* R[X]) P : ideal R[X]))
ring_equiv.is_domain (polynomial (R ⧸ P)) (polynomial_quotient_equiv_quotient_polynomial P).symm
lemma
ideal.is_domain_map_C_quotient
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "is_domain", "polynomial", "ring_equiv.is_domain" ]
If `P` is a prime ideal of `R`, then `R[x]/(P)` is an integral domain.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_zero_of_polynomial_mem_map_range (I : ideal R[X]) (x : ((quotient.mk I).comp C).range) (hx : C x ∈ (I.map (polynomial.map_ring_hom ((quotient.mk I).comp C).range_restrict))) : x = 0
begin let i := ((quotient.mk I).comp C).range_restrict, have hi' : (polynomial.map_ring_hom i).ker ≤ I, { refine λ f hf, polynomial_mem_ideal_of_coeff_mem_ideal I f (λ n, _), rw [mem_comap, ← quotient.eq_zero_iff_mem, ← ring_hom.comp_apply], rw [ring_hom.mem_ker, coe_map_ring_hom] at hf, replace hf :=...
lemma
ideal.eq_zero_of_polynomial_mem_map_range
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "polynomial", "polynomial.map_ring_hom", "polynomial.map_surjective", "ring_hom.coe_range_restrict", "ring_hom.comp_apply", "ring_hom.map_sub", "ring_hom.mem_ker", "ring_hom.mem_range", "subtype.ext_iff", "subtype.val_eq_coe" ]
Given any ring `R` and an ideal `I` of `R[X]`, we get a map `R → R[x] → R[x]/I`. If we let `R` be the image of `R` in `R[x]/I` then we also have a map `R[x] → R'[x]`. In particular we can map `I` across this map, to get `I'` and a new map `R' → R'[x] → R'[x]/I`. This theorem shows `I'` will not contain any non-ze...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quotient_map_C_eq_zero {I : ideal R} {i : R} (hi : i ∈ I) : (ideal.quotient.mk (ideal.map (C : R →+* mv_polynomial σ R) I : ideal (mv_polynomial σ R))).comp C i = 0
begin simp only [function.comp_app, ring_hom.coe_comp, ideal.quotient.eq_zero_iff_mem], exact ideal.mem_map_of_mem _ hi end
lemma
mv_polynomial.quotient_map_C_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "ideal.map", "ideal.mem_map_of_mem", "ideal.quotient.eq_zero_iff_mem", "ideal.quotient.mk", "mv_polynomial", "ring_hom.coe_comp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eval₂_C_mk_eq_zero {I : ideal R} {a : mv_polynomial σ R} (ha : a ∈ (ideal.map (C : R →+* mv_polynomial σ R) I : ideal (mv_polynomial σ R))) : eval₂_hom (C.comp (ideal.quotient.mk I)) X a = 0
begin rw as_sum a, rw [coe_eval₂_hom, eval₂_sum], refine finset.sum_eq_zero (λ n hn, _), simp only [eval₂_monomial, function.comp_app, ring_hom.coe_comp], refine mul_eq_zero_of_left _ _, suffices : coeff n a ∈ I, { rw [← @ideal.mk_ker R _ I, ring_hom.mem_ker] at this, simp only [this, C_0] }, exact ...
lemma
mv_polynomial.eval₂_C_mk_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "ideal.map", "ideal.mk_ker", "ideal.quotient.mk", "mul_eq_zero_of_left", "mv_polynomial", "ring_hom.coe_comp", "ring_hom.mem_ker" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quotient_equiv_quotient_mv_polynomial (I : ideal R) : mv_polynomial σ (R ⧸ I) ≃ₐ[R] mv_polynomial σ R ⧸ (ideal.map C I : ideal (mv_polynomial σ R))
{ to_fun := eval₂_hom (ideal.quotient.lift I ((ideal.quotient.mk (ideal.map C I : ideal (mv_polynomial σ R))).comp C) (λ i hi, quotient_map_C_eq_zero hi)) (λ i, ideal.quotient.mk (ideal.map C I : ideal (mv_polynomial σ R)) (X i)), inv_fun := ideal.quotient.lift (ideal.map C I : ideal (mv_polynomial σ R)) ...
def
mv_polynomial.quotient_equiv_quotient_mv_polynomial
ring_theory.polynomial
src/ring_theory/polynomial/quotient.lean
[ "data.polynomial.div", "ring_theory.polynomial.basic", "ring_theory.ideal.quotient_operations" ]
[ "ideal", "ideal.map", "ideal.quotient.lift", "ideal.quotient.lift_mk", "ideal.quotient.mk", "ideal.quotient.mk_eq_mk", "inv_fun", "mv_polynomial", "mv_polynomial.C_inj", "mv_polynomial.coe_eval₂_hom", "mv_polynomial.eval₂_add", "mv_polynomial.eval₂_hom_C", "ring_hom.coe_comp", "ring_hom.ma...
If `I` is an ideal of `R`, then the ring `mv_polynomial σ I.quotient` is isomorphic as an `R`-algebra to the quotient of `mv_polynomial σ R` by the ideal generated by `I`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
scale_roots_aeval_eq_zero_of_aeval_mk'_eq_zero {p : A[X]} {r : A} {s : M} (hr : aeval (mk' S r s) p = 0) : aeval (algebra_map A S r) (scale_roots p s) = 0
begin convert scale_roots_eval₂_eq_zero (algebra_map A S) hr, rw [aeval_def, mk'_spec' _ r s] end
lemma
scale_roots_aeval_eq_zero_of_aeval_mk'_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/rational_root.lean
[ "ring_theory.integrally_closed", "ring_theory.localization.num_denom", "ring_theory.polynomial.scale_roots" ]
[ "algebra_map", "mk'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
num_is_root_scale_roots_of_aeval_eq_zero [unique_factorization_monoid A] {p : A[X]} {x : K} (hr : aeval x p = 0) : is_root (scale_roots p (denom A x)) (num A x)
begin apply is_root_of_eval₂_map_eq_zero (is_fraction_ring.injective A K), refine scale_roots_aeval_eq_zero_of_aeval_mk'_eq_zero _, rw mk'_num_denom, exact hr end
lemma
num_is_root_scale_roots_of_aeval_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/rational_root.lean
[ "ring_theory.integrally_closed", "ring_theory.localization.num_denom", "ring_theory.polynomial.scale_roots" ]
[ "is_fraction_ring.injective", "num", "scale_roots_aeval_eq_zero_of_aeval_mk'_eq_zero", "unique_factorization_monoid" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
num_dvd_of_is_root {p : A[X]} {r : K} (hr : aeval r p = 0) : num A r ∣ p.coeff 0
begin suffices : num A r ∣ (scale_roots p (denom A r)).coeff 0, { simp only [coeff_scale_roots, tsub_zero] at this, haveI := classical.prop_decidable, by_cases hr : num A r = 0, { obtain ⟨u, hu⟩ := (is_unit_denom_of_num_eq_zero hr).pow p.nat_degree, rw ←hu at this, exact units.dvd_mul_right....
theorem
num_dvd_of_is_root
ring_theory.polynomial
src/ring_theory/polynomial/rational_root.lean
[ "ring_theory.integrally_closed", "ring_theory.localization.num_denom", "ring_theory.polynomial.scale_roots" ]
[ "dvd_mul_of_dvd_right", "mul_one", "num", "num_is_root_scale_roots_of_aeval_eq_zero", "pow_dvd_pow", "pow_one", "pow_zero", "tsub_zero" ]
Rational root theorem part 1: if `r : f.codomain` is a root of a polynomial over the ufd `A`, then the numerator of `r` divides the constant coefficient
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
denom_dvd_of_is_root {p : A[X]} {r : K} (hr : aeval r p = 0) : (denom A r : A) ∣ p.leading_coeff
begin suffices : (denom A r : A) ∣ p.leading_coeff * num A r ^ p.nat_degree, { refine dvd_of_dvd_mul_left_of_no_prime_factors (mem_non_zero_divisors_iff_ne_zero.mp (denom A r).2) _ this, intros q dvd_denom dvd_num_pow hq, apply hq.not_unit, exact num_denom_reduced A r (hq.dvd_of_dvd_pow dvd_num_po...
theorem
denom_dvd_of_is_root
ring_theory.polynomial
src/ring_theory/polynomial/rational_root.lean
[ "ring_theory.integrally_closed", "ring_theory.localization.num_denom", "ring_theory.polynomial.scale_roots" ]
[ "dvd_mul_of_dvd_right", "dvd_zero", "num", "num_is_root_scale_roots_of_aeval_eq_zero", "pow_dvd_pow", "pow_one", "zero_mul" ]
Rational root theorem part 2: if `r : f.codomain` is a root of a polynomial over the ufd `A`, then the denominator of `r` divides the leading coefficient
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_integer_of_is_root_of_monic {p : A[X]} (hp : monic p) {r : K} (hr : aeval r p = 0) : is_integer A r
is_integer_of_is_unit_denom (is_unit_of_dvd_one _ (hp ▸ denom_dvd_of_is_root hr))
theorem
is_integer_of_is_root_of_monic
ring_theory.polynomial
src/ring_theory/polynomial/rational_root.lean
[ "ring_theory.integrally_closed", "ring_theory.localization.num_denom", "ring_theory.polynomial.scale_roots" ]
[ "denom_dvd_of_is_root", "is_unit_of_dvd_one" ]
Integral root theorem: if `r : f.codomain` is a root of a monic polynomial over the ufd `A`, then `r` is an integer
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
integer_of_integral {x : K} : is_integral A x → is_integer A x
λ ⟨p, hp, hx⟩, is_integer_of_is_root_of_monic hp hx
lemma
unique_factorization_monoid.integer_of_integral
ring_theory.polynomial
src/ring_theory/polynomial/rational_root.lean
[ "ring_theory.integrally_closed", "ring_theory.localization.num_denom", "ring_theory.polynomial.scale_roots" ]
[ "is_integer_of_is_root_of_monic", "is_integral" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
scale_roots (p : R[X]) (s : R) : R[X]
∑ i in p.support, monomial i (p.coeff i * s ^ (p.nat_degree - i))
def
polynomial.scale_roots
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[]
`scale_roots p s` is a polynomial with root `r * s` for each root `r` of `p`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_scale_roots (p : R[X]) (s : R) (i : ℕ) : (scale_roots p s).coeff i = coeff p i * s ^ (p.nat_degree - i)
by simp [scale_roots, coeff_monomial] {contextual := tt}
lemma
polynomial.coeff_scale_roots
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_scale_roots_nat_degree (p : R[X]) (s : R) : (scale_roots p s).coeff p.nat_degree = p.leading_coeff
by rw [leading_coeff, coeff_scale_roots, tsub_self, pow_zero, mul_one]
lemma
polynomial.coeff_scale_roots_nat_degree
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "mul_one", "pow_zero", "tsub_self" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
zero_scale_roots (s : R) : scale_roots 0 s = 0
by { ext, simp }
lemma
polynomial.zero_scale_roots
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
scale_roots_ne_zero {p : R[X]} (hp : p ≠ 0) (s : R) : scale_roots p s ≠ 0
begin intro h, have : p.coeff p.nat_degree ≠ 0 := mt leading_coeff_eq_zero.mp hp, have : (scale_roots p s).coeff p.nat_degree = 0 := congr_fun (congr_arg (coeff : R[X] → ℕ → R) h) p.nat_degree, rw [coeff_scale_roots_nat_degree] at this, contradiction end
lemma
polynomial.scale_roots_ne_zero
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
support_scale_roots_le (p : R[X]) (s : R) : (scale_roots p s).support ≤ p.support
by { intro, simpa using left_ne_zero_of_mul }
lemma
polynomial.support_scale_roots_le
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "left_ne_zero_of_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
support_scale_roots_eq (p : R[X]) {s : R} (hs : s ∈ non_zero_divisors R) : (scale_roots p s).support = p.support
le_antisymm (support_scale_roots_le p s) begin intro i, simp only [coeff_scale_roots, polynomial.mem_support_iff], intros p_ne_zero ps_zero, have := pow_mem hs (p.nat_degree - i) _ ps_zero, contradiction end
lemma
polynomial.support_scale_roots_eq
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "non_zero_divisors", "polynomial.mem_support_iff", "pow_mem" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
degree_scale_roots (p : R[X]) {s : R} : degree (scale_roots p s) = degree p
begin haveI := classical.prop_decidable, by_cases hp : p = 0, { rw [hp, zero_scale_roots] }, have := scale_roots_ne_zero hp s, refine le_antisymm (finset.sup_mono (support_scale_roots_le p s)) (degree_le_degree _), rw coeff_scale_roots_nat_degree, intro h, have := leading_coeff_eq_zero.mp h, contradic...
lemma
polynomial.degree_scale_roots
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "finset.sup_mono" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nat_degree_scale_roots (p : R[X]) (s : R) : nat_degree (scale_roots p s) = nat_degree p
by simp only [nat_degree, degree_scale_roots]
lemma
polynomial.nat_degree_scale_roots
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
monic_scale_roots_iff {p : R[X]} (s : R) : monic (scale_roots p s) ↔ monic p
by simp only [monic, leading_coeff, nat_degree_scale_roots, coeff_scale_roots_nat_degree]
lemma
polynomial.monic_scale_roots_iff
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
scale_roots_eval₂_mul {p : S[X]} (f : S →+* R) (r : R) (s : S) : eval₂ f (f s * r) (scale_roots p s) = f s ^ p.nat_degree * eval₂ f r p
calc eval₂ f (f s * r) (scale_roots p s) = (scale_roots p s).support.sum (λ i, f (coeff p i * s ^ (p.nat_degree - i)) * (f s * r) ^ i) : by simp [eval₂_eq_sum, sum_def] ... = p.support.sum (λ i, f (coeff p i * s ^ (p.nat_degree - i)) * (f s * r) ^ i) : finset.sum_subset (support_scale_roots_le p s) (λ i hi hi',...
lemma
polynomial.scale_roots_eval₂_mul
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "mul_assoc", "mul_left_comm", "mul_pow", "pow_add", "tsub_add_cancel_of_le" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
scale_roots_eval₂_eq_zero {p : S[X]} (f : S →+* R) {r : R} {s : S} (hr : eval₂ f r p = 0) : eval₂ f (f s * r) (scale_roots p s) = 0
by rw [scale_roots_eval₂_mul, hr, _root_.mul_zero]
lemma
polynomial.scale_roots_eval₂_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
scale_roots_aeval_eq_zero [algebra S R] {p : S[X]} {r : R} {s : S} (hr : aeval r p = 0) : aeval (algebra_map S R s * r) (scale_roots p s) = 0
scale_roots_eval₂_eq_zero (algebra_map S R) hr
lemma
polynomial.scale_roots_aeval_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "algebra", "algebra_map" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
scale_roots_eval₂_eq_zero_of_eval₂_div_eq_zero {p : A[X]} {f : A →+* K} (hf : function.injective f) {r s : A} (hr : eval₂ f (f r / f s) p = 0) (hs : s ∈ non_zero_divisors A) : eval₂ f (f r) (scale_roots p s) = 0
begin convert scale_roots_eval₂_eq_zero f hr, rw [←mul_div_assoc, mul_comm, mul_div_cancel], exact map_ne_zero_of_mem_non_zero_divisors _ hf hs end
lemma
polynomial.scale_roots_eval₂_eq_zero_of_eval₂_div_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "map_ne_zero_of_mem_non_zero_divisors", "mul_comm", "mul_div_cancel", "non_zero_divisors" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
scale_roots_aeval_eq_zero_of_aeval_div_eq_zero [algebra A K] (inj : function.injective (algebra_map A K)) {p : A[X]} {r s : A} (hr : aeval (algebra_map A K r / algebra_map A K s) p = 0) (hs : s ∈ non_zero_divisors A) : aeval (algebra_map A K r) (scale_roots p s) = 0
scale_roots_eval₂_eq_zero_of_eval₂_div_eq_zero inj hr hs
lemma
polynomial.scale_roots_aeval_eq_zero_of_aeval_div_eq_zero
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "algebra", "algebra_map", "non_zero_divisors" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_scale_roots (p : R[X]) (x : R) (f : R →+* S) (h : f p.leading_coeff ≠ 0) : (p.scale_roots x).map f = (p.map f).scale_roots (f x)
begin ext, simp [polynomial.nat_degree_map_of_leading_coeff_ne_zero _ h], end
lemma
polynomial.map_scale_roots
ring_theory.polynomial
src/ring_theory/polynomial/scale_roots.lean
[ "ring_theory.non_zero_divisors", "data.polynomial.algebra_map" ]
[ "polynomial.nat_degree_map_of_leading_coeff_ne_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
X_pow_sub_X_sub_one_irreducible_aux (z : ℂ) : ¬ (z ^ n = z + 1 ∧ z ^ n + z ^ 2 = 0)
begin rintros ⟨h1, h2⟩, replace h3 : z ^ 3 = 1, { linear_combination (1 - z - z ^ 2 - z ^ n) * h1 + (z ^ n - 2) * h2 }, -- thanks polyrith! have key : z ^ n = 1 ∨ z ^ n = z ∨ z ^ n = z ^ 2, { rw [←nat.mod_add_div n 3, pow_add, pow_mul, h3, one_pow, mul_one], have : n % 3 < 3 := nat.mod_lt n zero_lt_three,...
lemma
polynomial.X_pow_sub_X_sub_one_irreducible_aux
ring_theory.polynomial
src/ring_theory/polynomial/selmer.lean
[ "data.polynomial.unit_trinomial", "ring_theory.polynomial.gauss_lemma", "tactic.linear_combination" ]
[ "add_self_eq_zero", "mul_one", "one_ne_zero", "one_pow", "pow_add", "pow_eq_zero", "pow_mul", "pow_one", "pow_zero", "zero_lt_three", "zero_ne_one", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
X_pow_sub_X_sub_one_irreducible (hn1 : n ≠ 1) : irreducible (X ^ n - X - 1 : ℤ[X])
begin by_cases hn0 : n = 0, { rw [hn0, pow_zero, sub_sub, add_comm, ←sub_sub, sub_self, zero_sub], exact associated.irreducible ⟨-1, mul_neg_one X⟩ irreducible_X }, have hn : 1 < n := nat.one_lt_iff_ne_zero_and_ne_one.mpr ⟨hn0, hn1⟩, have hp : (X ^ n - X - 1 : ℤ[X]) = trinomial 0 1 n (-1) (-1) 1 := by s...
lemma
polynomial.X_pow_sub_X_sub_one_irreducible
ring_theory.polynomial
src/ring_theory/polynomial/selmer.lean
[ "data.polynomial.unit_trinomial", "ring_theory.polynomial.gauss_lemma", "tactic.linear_combination" ]
[ "associated.irreducible", "irreducible", "map_one", "mul_assoc", "mul_eq_zero_of_left", "mul_neg_one", "ne_zero", "pow_zero", "ring", "units.coe_neg", "units.coe_one", "zero_lt_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
X_pow_sub_X_sub_one_irreducible_rat (hn1 : n ≠ 1) : irreducible (X ^ n - X - 1 : ℚ[X])
begin by_cases hn0 : n = 0, { rw [hn0, pow_zero, sub_sub, add_comm, ←sub_sub, sub_self, zero_sub], exact associated.irreducible ⟨-1, mul_neg_one X⟩ irreducible_X }, have hp : (X ^ n - X - 1 : ℤ[X]) = trinomial 0 1 n (-1) (-1) 1 := by simp only [trinomial, C_neg, C_1]; ring, have hn : 1 < n := nat.one_lt_i...
lemma
polynomial.X_pow_sub_X_sub_one_irreducible_rat
ring_theory.polynomial
src/ring_theory/polynomial/selmer.lean
[ "data.polynomial.unit_trinomial", "ring_theory.polynomial.gauss_lemma", "tactic.linear_combination" ]
[ "associated.irreducible", "irreducible", "mul_neg_one", "polynomial.map_X", "polynomial.map_one", "polynomial.map_pow", "polynomial.map_sub", "pow_zero", "ring", "zero_lt_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
aeval_map_algebra_map (x : B) (p : R[X]) : aeval x (map (algebra_map R A) p) = aeval x p
by rw [aeval_def, aeval_def, eval₂_map, is_scalar_tower.algebra_map_eq R A B]
theorem
polynomial.aeval_map_algebra_map
ring_theory.polynomial
src/ring_theory/polynomial/tower.lean
[ "algebra.algebra.tower", "data.polynomial.algebra_map" ]
[ "algebra_map", "is_scalar_tower.algebra_map_eq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
aeval_algebra_map_apply (x : A) (p : R[X]) : aeval (algebra_map A B x) p = algebra_map A B (aeval x p)
by rw [aeval_def, aeval_def, hom_eval₂, ←is_scalar_tower.algebra_map_eq]
lemma
polynomial.aeval_algebra_map_apply
ring_theory.polynomial
src/ring_theory/polynomial/tower.lean
[ "algebra.algebra.tower", "data.polynomial.algebra_map" ]
[ "algebra_map" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
aeval_algebra_map_eq_zero_iff [no_zero_smul_divisors A B] [nontrivial B] (x : A) (p : R[X]) : aeval (algebra_map A B x) p = 0 ↔ aeval x p = 0
by rw [aeval_algebra_map_apply, algebra.algebra_map_eq_smul_one, smul_eq_zero, iff_false_intro (one_ne_zero' B), or_false]
lemma
polynomial.aeval_algebra_map_eq_zero_iff
ring_theory.polynomial
src/ring_theory/polynomial/tower.lean
[ "algebra.algebra.tower", "data.polynomial.algebra_map" ]
[ "algebra.algebra_map_eq_smul_one", "algebra_map", "no_zero_smul_divisors", "nontrivial", "one_ne_zero'", "smul_eq_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
aeval_algebra_map_eq_zero_iff_of_injective {x : A} {p : R[X]} (h : function.injective (algebra_map A B)) : aeval (algebra_map A B x) p = 0 ↔ aeval x p = 0
by rw [aeval_algebra_map_apply, ← (algebra_map A B).map_zero, h.eq_iff]
lemma
polynomial.aeval_algebra_map_eq_zero_iff_of_injective
ring_theory.polynomial
src/ring_theory/polynomial/tower.lean
[ "algebra.algebra.tower", "data.polynomial.algebra_map" ]
[ "algebra_map" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
aeval_coe (S : subalgebra R A) (x : S) (p : R[X]) : aeval (x : A) p = aeval x p
aeval_algebra_map_apply A x p
lemma
subalgebra.aeval_coe
ring_theory.polynomial
src/ring_theory/polynomial/tower.lean
[ "algebra.algebra.tower", "data.polynomial.algebra_map" ]
[ "subalgebra" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
prod_X_add_C_eq_sum_esymm (s : multiset R) : (s.map (λ r, X + C r)).prod = ∑ j in finset.range (s.card + 1), C (s.esymm j) * X ^ (s.card - j)
begin classical, rw [prod_map_add, antidiagonal_eq_map_powerset, map_map, ←bind_powerset_len, function.comp, map_bind, sum_bind, finset.sum_eq_multiset_sum, finset.range_val, map_congr (eq.refl _)], intros _ _, rw [esymm, ←sum_hom', ←sum_map_mul_right, map_congr (eq.refl _)], intros _ ht, rw mem_powerse...
lemma
multiset.prod_X_add_C_eq_sum_esymm
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "finset.range", "finset.range_val", "map_bind", "map_congr", "multiset" ]
A sum version of Vieta's formula for `multiset`: the product of the linear terms `X + λ` where `λ` runs through a multiset `s` is equal to a linear combination of the symmetric functions `esymm s` of the `λ`'s .
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
prod_X_add_C_coeff (s : multiset R) {k : ℕ} (h : k ≤ s.card) : (s.map (λ r, X + C r)).prod.coeff k = s.esymm (s.card - k)
begin convert polynomial.ext_iff.mp (prod_X_add_C_eq_sum_esymm s) k, simp_rw [finset_sum_coeff, coeff_C_mul_X_pow], rw finset.sum_eq_single_of_mem (s.card - k) _, { rw if_pos (nat.sub_sub_self h).symm, }, { intros j hj1 hj2, suffices : k ≠ card s - j, { rw if_neg this, }, { intro hn, rw [hn,...
lemma
multiset.prod_X_add_C_coeff
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "finset.mem_range", "multiset" ]
Vieta's formula for the coefficients of the product of linear terms `X + λ` where `λ` runs through a multiset `s` : the `k`th coefficient is the symmetric function `esymm (card s - k) s`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
prod_X_add_C_coeff' {σ} (s : multiset σ) (r : σ → R) {k : ℕ} (h : k ≤ s.card) : (s.map (λ i, X + C (r i))).prod.coeff k = (s.map r).esymm (s.card - k)
by rw [← map_map (λ r, X + C r) r, prod_X_add_C_coeff]; rwa s.card_map r
lemma
multiset.prod_X_add_C_coeff'
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "multiset" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
_root_.finset.prod_X_add_C_coeff {σ} (s : finset σ) (r : σ → R) {k : ℕ} (h : k ≤ s.card) : (∏ i in s, (X + C (r i))).coeff k = ∑ t in s.powerset_len (s.card - k), ∏ i in t, r i
by { rw [finset.prod, prod_X_add_C_coeff' _ r h, finset.esymm_map_val], refl }
lemma
finset.prod_X_add_C_coeff
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "finset", "finset.esymm_map_val", "finset.prod" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
esymm_neg (s : multiset R) (k : ℕ) : (map has_neg.neg s).esymm k = (-1) ^ k * esymm s k
begin rw [esymm, esymm, ←multiset.sum_map_mul_left, multiset.powerset_len_map, multiset.map_map, map_congr (eq.refl _)], intros x hx, rw [(by { exact (mem_powerset_len.mp hx).right.symm }), ←prod_replicate, ←multiset.map_const], nth_rewrite 2 ←map_id' x, rw [←prod_map_mul, map_congr (eq.refl _)], exact ...
lemma
multiset.esymm_neg
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "map_congr", "multiset", "multiset.map_map", "multiset.powerset_len_map", "neg_one_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
prod_X_sub_C_eq_sum_esymm (s : multiset R) : (s.map (λ t, X - C t)).prod = ∑ j in finset.range (s.card + 1), (-1) ^ j * (C (s.esymm j) * X ^ (s.card - j))
begin conv_lhs { congr, congr, funext, rw sub_eq_add_neg, rw ←map_neg C _, }, convert prod_X_add_C_eq_sum_esymm (map (λ t, -t) s) using 1, { rwa map_map, }, { simp only [esymm_neg, card_map, mul_assoc, map_mul, map_pow, map_neg, map_one], }, end
lemma
multiset.prod_X_sub_C_eq_sum_esymm
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "finset.range", "map_mul", "map_one", "map_pow", "mul_assoc", "multiset" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
prod_X_sub_C_coeff (s : multiset R) {k : ℕ} (h : k ≤ s.card) : (s.map (λ t, X - C t)).prod.coeff k = (-1) ^ (s.card - k) * s.esymm (s.card - k)
begin conv_lhs { congr, congr, congr, funext, rw sub_eq_add_neg, rw ←map_neg C _, }, convert prod_X_add_C_coeff (map (λ t, -t) s) _ using 1, { rwa map_map, }, { rwa [esymm_neg, card_map] }, { rwa card_map }, end
lemma
multiset.prod_X_sub_C_coeff
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "multiset" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
_root_.polynomial.coeff_eq_esymm_roots_of_card [is_domain R] {p : R[X]} (hroots : p.roots.card = p.nat_degree) {k : ℕ} (h : k ≤ p.nat_degree) : p.coeff k = p.leading_coeff * (-1) ^ (p.nat_degree - k) * p.roots.esymm (p.nat_degree - k)
begin conv_lhs { rw ← C_leading_coeff_mul_prod_multiset_X_sub_C hroots }, rw [coeff_C_mul, mul_assoc], congr, convert p.roots.prod_X_sub_C_coeff _ using 3; rw hroots, exact h, end
theorem
polynomial.coeff_eq_esymm_roots_of_card
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "is_domain", "mul_assoc" ]
Vieta's formula for the coefficients and the roots of a polynomial over an integral domain with as many roots as its degree.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
_root_.polynomial.coeff_eq_esymm_roots_of_splits {F} [field F] {p : F[X]} (hsplit : p.splits (ring_hom.id F)) {k : ℕ} (h : k ≤ p.nat_degree) : p.coeff k = p.leading_coeff * (-1) ^ (p.nat_degree - k) * p.roots.esymm (p.nat_degree - k)
polynomial.coeff_eq_esymm_roots_of_card (splits_iff_card_roots.1 hsplit) h
theorem
polynomial.coeff_eq_esymm_roots_of_splits
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "field", "polynomial.coeff_eq_esymm_roots_of_card", "ring_hom.id" ]
Vieta's formula for split polynomials over a field.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mv_polynomial.prod_C_add_X_eq_sum_esymm : ∏ i : σ, (X + C (mv_polynomial.X i)) = ∑ j in range (card σ + 1), (C (mv_polynomial.esymm σ R j) * X ^ (card σ - j))
begin let s := finset.univ.val.map (λ i : σ, mv_polynomial.X i), rw (_ : card σ = s.card), { simp_rw [mv_polynomial.esymm_eq_multiset_esymm σ R, finset.prod_eq_multiset_prod], convert multiset.prod_X_add_C_eq_sum_esymm s, rwa multiset.map_map, }, { rw multiset.card_map, refl, } end
lemma
mv_polynomial.prod_C_add_X_eq_sum_esymm
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "finset.prod_eq_multiset_prod", "multiset.card_map", "multiset.map_map", "multiset.prod_X_add_C_eq_sum_esymm", "mv_polynomial.X", "mv_polynomial.esymm", "mv_polynomial.esymm_eq_multiset_esymm" ]
A sum version of Vieta's formula for `mv_polynomial`: viewing `X i` as variables, the product of linear terms `λ + X i` is equal to a linear combination of the symmetric polynomials `esymm σ R j`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mv_polynomial.prod_X_add_C_coeff (k : ℕ) (h : k ≤ card σ) : (∏ i : σ, (X + C (mv_polynomial.X i))).coeff k = mv_polynomial.esymm σ R (card σ - k)
begin let s := finset.univ.val.map (λ i, (mv_polynomial.X i : mv_polynomial σ R)), rw (_ : card σ = s.card) at ⊢ h, { rw [mv_polynomial.esymm_eq_multiset_esymm σ R, finset.prod_eq_multiset_prod], convert multiset.prod_X_add_C_coeff s h, rwa multiset.map_map }, repeat { rw multiset.card_map, refl, }, end
lemma
mv_polynomial.prod_X_add_C_coeff
ring_theory.polynomial
src/ring_theory/polynomial/vieta.lean
[ "data.polynomial.splits", "ring_theory.mv_polynomial.symmetric" ]
[ "finset.prod_eq_multiset_prod", "multiset.card_map", "multiset.map_map", "multiset.prod_X_add_C_coeff", "mv_polynomial", "mv_polynomial.X", "mv_polynomial.esymm", "mv_polynomial.esymm_eq_multiset_esymm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cyclotomic' (n : ℕ) (R : Type*) [comm_ring R] [is_domain R] : R[X]
∏ μ in primitive_roots n R, (X - C μ)
def
polynomial.cyclotomic'
ring_theory.polynomial.cyclotomic
src/ring_theory/polynomial/cyclotomic/basic.lean
[ "algebra.ne_zero", "algebra.polynomial.big_operators", "ring_theory.roots_of_unity.complex", "data.polynomial.lifts", "data.polynomial.splits", "data.zmod.algebra", "field_theory.ratfunc", "field_theory.separable", "number_theory.arithmetic_function", "ring_theory.roots_of_unity.basic" ]
[ "comm_ring", "is_domain", "primitive_roots" ]
The modified `n`-th cyclotomic polynomial with coefficients in `R`, it is the usual cyclotomic polynomial if there is a primitive `n`-th root of unity in `R`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cyclotomic'_zero (R : Type*) [comm_ring R] [is_domain R] : cyclotomic' 0 R = 1
by simp only [cyclotomic', finset.prod_empty, primitive_roots_zero]
lemma
polynomial.cyclotomic'_zero
ring_theory.polynomial.cyclotomic
src/ring_theory/polynomial/cyclotomic/basic.lean
[ "algebra.ne_zero", "algebra.polynomial.big_operators", "ring_theory.roots_of_unity.complex", "data.polynomial.lifts", "data.polynomial.splits", "data.zmod.algebra", "field_theory.ratfunc", "field_theory.separable", "number_theory.arithmetic_function", "ring_theory.roots_of_unity.basic" ]
[ "comm_ring", "finset.prod_empty", "is_domain", "primitive_roots_zero" ]
The zeroth modified cyclotomic polyomial is `1`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cyclotomic'_one (R : Type*) [comm_ring R] [is_domain R] : cyclotomic' 1 R = X - 1
begin simp only [cyclotomic', finset.prod_singleton, ring_hom.map_one, is_primitive_root.primitive_roots_one] end
lemma
polynomial.cyclotomic'_one
ring_theory.polynomial.cyclotomic
src/ring_theory/polynomial/cyclotomic/basic.lean
[ "algebra.ne_zero", "algebra.polynomial.big_operators", "ring_theory.roots_of_unity.complex", "data.polynomial.lifts", "data.polynomial.splits", "data.zmod.algebra", "field_theory.ratfunc", "field_theory.separable", "number_theory.arithmetic_function", "ring_theory.roots_of_unity.basic" ]
[ "comm_ring", "finset.prod_singleton", "is_domain", "is_primitive_root.primitive_roots_one", "ring_hom.map_one" ]
The first modified cyclotomic polyomial is `X - 1`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83