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frobenius_eq_map_frobenius : @frobenius p R _ _ = map (_root_.frobenius R p)
begin ext x n, simp only [coeff_frobenius_char_p, map_coeff, frobenius_def], end
lemma
witt_vector.frobenius_eq_map_frobenius
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius.lean
[ "data.nat.multiplicity", "data.zmod.algebra", "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly", "field_theory.perfect_closure" ]
[ "frobenius", "frobenius_def" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
frobenius_zmodp (x : 𝕎 (zmod p)) : (frobenius x) = x
by simp only [ext_iff, coeff_frobenius_char_p, zmod.pow_card, eq_self_iff_true, forall_const]
lemma
witt_vector.frobenius_zmodp
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius.lean
[ "data.nat.multiplicity", "data.zmod.algebra", "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly", "field_theory.perfect_closure" ]
[ "forall_const", "frobenius", "zmod", "zmod.pow_card" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
frobenius_equiv [perfect_ring R p] : witt_vector p R ≃+* witt_vector p R
{ to_fun := witt_vector.frobenius, inv_fun := map (pth_root R p), left_inv := λ f, ext $ λ n, by { rw frobenius_eq_map_frobenius, exact pth_root_frobenius _ }, right_inv := λ f, ext $ λ n, by { rw frobenius_eq_map_frobenius, exact frobenius_pth_root _ }, ..(witt_vector.frobenius : witt_vector p R →+* witt_vect...
def
witt_vector.frobenius_equiv
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius.lean
[ "data.nat.multiplicity", "data.zmod.algebra", "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly", "field_theory.perfect_closure" ]
[ "frobenius_equiv", "frobenius_pth_root", "inv_fun", "perfect_ring", "pth_root", "pth_root_frobenius", "witt_vector", "witt_vector.frobenius" ]
`witt_vector.frobenius` as an equiv.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
frobenius_bijective [perfect_ring R p] : function.bijective (@witt_vector.frobenius p R _ _)
(frobenius_equiv p R).bijective
lemma
witt_vector.frobenius_bijective
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius.lean
[ "data.nat.multiplicity", "data.zmod.algebra", "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly", "field_theory.perfect_closure" ]
[ "frobenius_equiv", "perfect_ring", "witt_vector.frobenius" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
succ_nth_defining_poly (n : ℕ) (a₁ a₂ : 𝕎 k) (bs : fin (n+1) → k) : polynomial k
X^p * C (a₁.coeff 0 ^ (p^(n+1))) - X * C (a₂.coeff 0 ^ (p^(n+1))) + C (a₁.coeff (n+1) * ((bs 0)^p)^(p^(n+1)) + nth_remainder p n (λ v, (bs v)^p) (truncate_fun (n+1) a₁) - a₂.coeff (n+1) * (bs 0)^p^(n+1) - nth_remainder p n bs (truncate_fun (n+1) a₂))
def
witt_vector.recursion_main.succ_nth_defining_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "polynomial" ]
The root of this polynomial determines the `n+1`st coefficient of our solution.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
succ_nth_defining_poly_degree [is_domain k] (n : ℕ) (a₁ a₂ : 𝕎 k) (bs : fin (n+1) → k) (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : (succ_nth_defining_poly p n a₁ a₂ bs).degree = p
begin have : (X ^ p * C (a₁.coeff 0 ^ p ^ (n+1))).degree = p, { rw [degree_mul, degree_C], { simp only [nat.cast_with_bot, add_zero, degree_X, degree_pow, nat.smul_one_eq_coe] }, { exact pow_ne_zero _ ha₁ } }, have : (X ^ p * C (a₁.coeff 0 ^ p ^ (n+1)) - X * C (a₂.coeff 0 ^ p ^ (n+1))).degree = p, { rw ...
lemma
witt_vector.recursion_main.succ_nth_defining_poly_degree
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "is_domain", "nat.cast_with_bot", "nat.smul_one_eq_coe", "pow_ne_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
root_exists (n : ℕ) (a₁ a₂ : 𝕎 k) (bs : fin (n+1) → k) (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : ∃ b : k, (succ_nth_defining_poly p n a₁ a₂ bs).is_root b
is_alg_closed.exists_root _ $ by simp only [(succ_nth_defining_poly_degree p n a₁ a₂ bs ha₁ ha₂), hp.out.ne_zero, with_top.coe_eq_zero, ne.def, not_false_iff]
lemma
witt_vector.recursion_main.root_exists
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "is_alg_closed.exists_root" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
succ_nth_val (n : ℕ) (a₁ a₂ : 𝕎 k) (bs : fin (n+1) → k) (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : k
classical.some (root_exists p n a₁ a₂ bs ha₁ ha₂)
def
witt_vector.recursion_main.succ_nth_val
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[]
This is the `n+1`st coefficient of our solution, projected from `root_exists`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
succ_nth_val_spec (n : ℕ) (a₁ a₂ : 𝕎 k) (bs : fin (n+1) → k) (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : (succ_nth_defining_poly p n a₁ a₂ bs).is_root (succ_nth_val p n a₁ a₂ bs ha₁ ha₂)
classical.some_spec (root_exists p n a₁ a₂ bs ha₁ ha₂)
lemma
witt_vector.recursion_main.succ_nth_val_spec
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
succ_nth_val_spec' (n : ℕ) (a₁ a₂ : 𝕎 k) (bs : fin (n+1) → k) (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : (succ_nth_val p n a₁ a₂ bs ha₁ ha₂)^p * a₁.coeff 0 ^ (p^(n+1)) + a₁.coeff (n+1) * ((bs 0)^p)^(p^(n+1)) + nth_remainder p n (λ v, (bs v)^p) (truncate_fun (n+1) a₁) = (succ_nth_val p n a₁ a₂ bs ha...
begin rw ← sub_eq_zero, have := succ_nth_val_spec p n a₁ a₂ bs ha₁ ha₂, simp only [polynomial.map_add, polynomial.eval_X, polynomial.map_pow, polynomial.eval_C, polynomial.eval_pow, succ_nth_defining_poly, polynomial.eval_mul, polynomial.eval_add, polynomial.eval_sub, polynomial.map_mul, polynomial.map_su...
lemma
witt_vector.recursion_main.succ_nth_val_spec'
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "polynomial.eval_C", "polynomial.eval_X", "polynomial.eval_add", "polynomial.eval_mul", "polynomial.eval_pow", "polynomial.eval_sub", "polynomial.is_root.def", "polynomial.map_add", "polynomial.map_mul", "polynomial.map_pow", "polynomial.map_sub", "ring" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
solution_pow (a₁ a₂ : 𝕎 k) : ∃ x : k, x^(p-1) = a₂.coeff 0 / a₁.coeff 0
is_alg_closed.exists_pow_nat_eq _ $ by linarith [hp.out.one_lt, le_of_lt hp.out.one_lt]
lemma
witt_vector.recursion_base.solution_pow
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "is_alg_closed.exists_pow_nat_eq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
solution (a₁ a₂ : 𝕎 k) : k
classical.some $ solution_pow p a₁ a₂
def
witt_vector.recursion_base.solution
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[]
The base case (0th coefficient) of our solution vector.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
solution_spec (a₁ a₂ : 𝕎 k) : (solution p a₁ a₂)^(p-1) = a₂.coeff 0 / a₁.coeff 0
classical.some_spec $ solution_pow p a₁ a₂
lemma
witt_vector.recursion_base.solution_spec
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
solution_nonzero {a₁ a₂ : 𝕎 k} (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : solution p a₁ a₂ ≠ 0
begin intro h, have := solution_spec p a₁ a₂, rw [h, zero_pow] at this, { simpa [ha₁, ha₂] using _root_.div_eq_zero_iff.mp this.symm }, { linarith [hp.out.one_lt, le_of_lt hp.out.one_lt] } end
lemma
witt_vector.recursion_base.solution_nonzero
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
solution_spec' {a₁ : 𝕎 k} (ha₁ : a₁.coeff 0 ≠ 0) (a₂ : 𝕎 k) : (solution p a₁ a₂)^p * a₁.coeff 0 = (solution p a₁ a₂) * a₂.coeff 0
begin have := solution_spec p a₁ a₂, cases nat.exists_eq_succ_of_ne_zero hp.out.ne_zero with q hq, have hq' : q = p - 1 := by simp only [hq, tsub_zero, nat.succ_sub_succ_eq_sub], conv_lhs {congr, congr, skip, rw hq}, rw [pow_succ', hq', this], field_simp [ha₁, mul_comm], end
lemma
witt_vector.recursion_base.solution_spec'
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "mul_comm", "pow_succ'", "tsub_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
frobenius_rotation_coeff {a₁ a₂ : 𝕎 k} (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : ℕ → k
| 0 := solution p a₁ a₂ | (n + 1) := succ_nth_val p n a₁ a₂ (λ i, frobenius_rotation_coeff i.val) ha₁ ha₂ using_well_founded { dec_tac := `[apply fin.is_lt] }
def
witt_vector.frobenius_rotation_coeff
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "fin.is_lt" ]
Recursively defines the sequence of coefficients for `witt_vector.frobenius_rotation`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
frobenius_rotation {a₁ a₂ : 𝕎 k} (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : 𝕎 k
witt_vector.mk p (frobenius_rotation_coeff p ha₁ ha₂)
def
witt_vector.frobenius_rotation
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[]
For nonzero `a₁` and `a₂`, `frobenius_rotation a₁ a₂` is a Witt vector that satisfies the equation `frobenius (frobenius_rotation a₁ a₂) * a₁ = (frobenius_rotation a₁ a₂) * a₂`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
frobenius_rotation_nonzero {a₁ a₂ : 𝕎 k} (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : frobenius_rotation p ha₁ ha₂ ≠ 0
begin intro h, apply solution_nonzero p ha₁ ha₂, simpa [← h, frobenius_rotation, frobenius_rotation_coeff] using witt_vector.zero_coeff p k 0 end
lemma
witt_vector.frobenius_rotation_nonzero
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "witt_vector.zero_coeff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
frobenius_frobenius_rotation {a₁ a₂ : 𝕎 k} (ha₁ : a₁.coeff 0 ≠ 0) (ha₂ : a₂.coeff 0 ≠ 0) : frobenius (frobenius_rotation p ha₁ ha₂) * a₁ = (frobenius_rotation p ha₁ ha₂) * a₂
begin ext n, induction n with n ih, { simp only [witt_vector.mul_coeff_zero, witt_vector.coeff_frobenius_char_p, frobenius_rotation, frobenius_rotation_coeff], apply solution_spec' _ ha₁ }, { simp only [nth_remainder_spec, witt_vector.coeff_frobenius_char_p, frobenius_rotation_coeff, frobenius_r...
lemma
witt_vector.frobenius_frobenius_rotation
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "fin.val_eq_coe", "frobenius", "ih", "truncated_witt_vector.ext", "witt_vector.coeff_frobenius_char_p", "witt_vector.coeff_truncate_fun", "witt_vector.mul_coeff_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
exists_frobenius_solution_fraction_ring_aux (m n : ℕ) (r' q' : 𝕎 k) (hr' : r'.coeff 0 ≠ 0) (hq' : q'.coeff 0 ≠ 0) (hq : ↑p ^ n * q' ∈ non_zero_divisors (𝕎 k)) : let b : 𝕎 k
frobenius_rotation p hr' hq' in is_fraction_ring.field_equiv_of_ring_equiv (frobenius_equiv p k) (algebra_map (𝕎 k) (fraction_ring (𝕎 k)) b) * localization.mk (↑p ^ m * r') ⟨↑p ^ n * q', hq⟩ = ↑p ^ (m - n : ℤ) * algebra_map (𝕎 k) (fraction_ring (𝕎 k)) b := begin intros b, have key : witt_vec...
lemma
witt_vector.exists_frobenius_solution_fraction_ring_aux
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "algebra_map", "fraction_ring", "frobenius_equiv", "is_fraction_ring.field_equiv_of_ring_equiv", "is_fraction_ring.injective", "is_localization.ring_equiv_of_ring_equiv_eq", "localization.mk", "map_nat_cast", "non_zero_divisors", "ring", "ring_equiv.coe_of_bijective", "ring_hom.map_mul", "ri...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
exists_frobenius_solution_fraction_ring {a : fraction_ring (𝕎 k)} (ha : a ≠ 0) : ∃ (b : fraction_ring (𝕎 k)) (hb : b ≠ 0) (m : ℤ), φ b * a = p ^ m * b
begin revert ha, refine localization.induction_on a _, rintros ⟨r, q, hq⟩ hrq, have hq0 : q ≠ 0 := mem_non_zero_divisors_iff_ne_zero.1 hq, have hr0 : r ≠ 0 := λ h, hrq (by simp [h]), obtain ⟨m, r', hr', rfl⟩ := exists_eq_pow_p_mul r hr0, obtain ⟨n, q', hq', rfl⟩ := exists_eq_pow_p_mul q hq0, let b := fr...
lemma
witt_vector.exists_frobenius_solution_fraction_ring
ring_theory.witt_vector
src/ring_theory/witt_vector/frobenius_fraction_field.lean
[ "data.nat.cast.with_top", "field_theory.is_alg_closed.basic", "ring_theory.witt_vector.discrete_valuation_ring" ]
[ "fraction_ring", "is_fraction_ring.injective", "localization.induction_on", "witt_vector" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
frobenius_verschiebung (x : 𝕎 R) : frobenius (verschiebung x) = x * p
by { ghost_calc x, ghost_simp [mul_comm] }
lemma
witt_vector.frobenius_verschiebung
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "frobenius", "mul_comm" ]
The composition of Frobenius and Verschiebung is multiplication by `p`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
verschiebung_zmod (x : 𝕎 (zmod p)) : verschiebung x = x * p
by rw [← frobenius_verschiebung, frobenius_zmodp]
lemma
witt_vector.verschiebung_zmod
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "zmod" ]
Verschiebung is the same as multiplication by `p` on the ring of Witt vectors of `zmod p`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_p_pow [char_p R p] (i : ℕ) : (p ^ i : 𝕎 R).coeff i = 1
begin induction i with i h, { simp only [one_coeff_zero, ne.def, pow_zero] }, { rw [pow_succ', ← frobenius_verschiebung, coeff_frobenius_char_p, verschiebung_coeff_succ, h, one_pow], } end
lemma
witt_vector.coeff_p_pow
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "one_pow", "pow_succ'", "pow_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_p_pow_eq_zero [char_p R p] {i j : ℕ} (hj : j ≠ i) : (p ^ i : 𝕎 R).coeff j = 0
begin induction i with i hi generalizing j, { rw [pow_zero, one_coeff_eq_of_pos], exact nat.pos_of_ne_zero hj }, { rw [pow_succ', ← frobenius_verschiebung, coeff_frobenius_char_p], cases j, { rw [verschiebung_coeff_zero, zero_pow], exact nat.prime.pos hp.out }, { rw [verschiebung_coeff_succ,...
lemma
witt_vector.coeff_p_pow_eq_zero
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "nat.prime.pos", "ne_of_apply_ne", "pow_succ'", "pow_zero", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_p [char_p R p] (i : ℕ) : (p : 𝕎 R).coeff i = if i = 1 then 1 else 0
begin split_ifs with hi, { simpa only [hi, pow_one] using coeff_p_pow p R 1, }, { simpa only [pow_one] using coeff_p_pow_eq_zero p R hi, } end
lemma
witt_vector.coeff_p
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "pow_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_p_zero [char_p R p] : (p : 𝕎 R).coeff 0 = 0
by { rw [coeff_p, if_neg], exact zero_ne_one }
lemma
witt_vector.coeff_p_zero
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "zero_ne_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_p_one [char_p R p] : (p : 𝕎 R).coeff 1 = 1
by rw [coeff_p, if_pos rfl]
lemma
witt_vector.coeff_p_one
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
p_nonzero [nontrivial R] [char_p R p] : (p : 𝕎 R) ≠ 0
by { intros h, simpa only [h, zero_coeff, zero_ne_one] using coeff_p_one p R }
lemma
witt_vector.p_nonzero
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "nontrivial", "zero_ne_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
fraction_ring.p_nonzero [nontrivial R] [char_p R p] : (p : fraction_ring (𝕎 R)) ≠ 0
by simpa using (is_fraction_ring.injective (𝕎 R) (fraction_ring (𝕎 R))).ne (p_nonzero _ _)
lemma
witt_vector.fraction_ring.p_nonzero
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "fraction_ring", "is_fraction_ring.injective", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
verschiebung_mul_frobenius (x y : 𝕎 R) : verschiebung (x * frobenius y) = verschiebung x * y
by { ghost_calc x y, rintro ⟨⟩; ghost_simp [mul_assoc] }
lemma
witt_vector.verschiebung_mul_frobenius
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "frobenius", "mul_assoc" ]
The “projection formula” for Frobenius and Verschiebung.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_char_p_coeff_zero [char_p R p] (x : 𝕎 R) : (x * p).coeff 0 = 0
begin rw [← frobenius_verschiebung, coeff_frobenius_char_p, verschiebung_coeff_zero, zero_pow], exact nat.prime.pos hp.out end
lemma
witt_vector.mul_char_p_coeff_zero
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "nat.prime.pos", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_char_p_coeff_succ [char_p R p] (x : 𝕎 R) (i : ℕ) : (x * p).coeff (i + 1) = (x.coeff i)^p
by rw [← frobenius_verschiebung, coeff_frobenius_char_p, verschiebung_coeff_succ]
lemma
witt_vector.mul_char_p_coeff_succ
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
verschiebung_frobenius [char_p R p] (x : 𝕎 R) : verschiebung (frobenius x) = x * p
begin ext ⟨i⟩, { rw [mul_char_p_coeff_zero, verschiebung_coeff_zero], }, { rw [mul_char_p_coeff_succ, verschiebung_coeff_succ, coeff_frobenius_char_p], } end
lemma
witt_vector.verschiebung_frobenius
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "frobenius" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
verschiebung_frobenius_comm [char_p R p] : function.commute (verschiebung : 𝕎 R → 𝕎 R) frobenius
λ x, by rw [verschiebung_frobenius, frobenius_verschiebung]
lemma
witt_vector.verschiebung_frobenius_comm
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "char_p", "frobenius", "function.commute" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iterate_verschiebung_coeff (x : 𝕎 R) (n k : ℕ) : (verschiebung^[n] x).coeff (k + n) = x.coeff k
begin induction n with k ih, { simp }, { rw [iterate_succ_apply', nat.add_succ, verschiebung_coeff_succ], exact ih } end
lemma
witt_vector.iterate_verschiebung_coeff
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "ih" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iterate_verschiebung_mul_left (x y : 𝕎 R) (i : ℕ) : (verschiebung^[i] x) * y = (verschiebung^[i] (x * (frobenius^[i] y)))
begin induction i with i ih generalizing y, { simp }, { rw [iterate_succ_apply', ← verschiebung_mul_frobenius, ih, iterate_succ_apply'], refl } end
lemma
witt_vector.iterate_verschiebung_mul_left
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "frobenius", "ih" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iterate_verschiebung_mul (x y : 𝕎 R) (i j : ℕ) : (verschiebung^[i] x) * (verschiebung^[j] y) = (verschiebung^[i + j] ((frobenius^[j] x) * (frobenius^[i] y)))
begin calc _ = (verschiebung^[i] (x * (frobenius^[i] ((verschiebung^[j] y))))) : _ ... = (verschiebung^[i] (x * (verschiebung^[j] ((frobenius^[i] y))))) : _ ... = (verschiebung^[i] ((verschiebung^[j] ((frobenius^[i] y)) * x))) : _ ... = (verschiebung^[i] ((verschiebung^[j] ((frobenius^[i] y) * (frobenius^[j] x)))))...
lemma
witt_vector.iterate_verschiebung_mul
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "frobenius", "mul_comm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iterate_frobenius_coeff (x : 𝕎 R) (i k : ℕ) : ((frobenius^[i] x)).coeff k = (x.coeff k)^(p^i)
begin induction i with i ih, { simp }, { rw [iterate_succ_apply', coeff_frobenius_char_p, ih], ring_exp } end
lemma
witt_vector.iterate_frobenius_coeff
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "frobenius", "ih" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
iterate_verschiebung_mul_coeff (x y : 𝕎 R) (i j : ℕ) : ((verschiebung^[i] x) * (verschiebung^[j] y)).coeff (i + j) = (x.coeff 0)^(p ^ j) * (y.coeff 0)^(p ^ i)
begin calc _ = (verschiebung^[i + j] ((frobenius^[j] x) * (frobenius^[i] y))).coeff (i + j) : _ ... = ((frobenius^[j] x) * (frobenius^[i] y)).coeff 0 : _ ... = (frobenius^[j] x).coeff 0 * ((frobenius^[i] y)).coeff 0 : _ ... = _ : _, { rw iterate_verschiebung_mul }, { convert iterate_verschiebung_coeff _ _ _ usi...
lemma
witt_vector.iterate_verschiebung_mul_coeff
ring_theory.witt_vector
src/ring_theory/witt_vector/identities.lean
[ "ring_theory.witt_vector.frobenius", "ring_theory.witt_vector.verschiebung", "ring_theory.witt_vector.mul_p" ]
[ "frobenius" ]
This is a slightly specialized form of [Hazewinkel, *Witt Vectors*][Haze09] 6.2 equation 5.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_ring (assert : parse (tk "using" *> parser.pexpr)?) : tactic unit
do `[rw ext_iff, intros i, simp only [init, select, coeff_mk], split_ifs with hi; try {refl}], match assert with | none := skip | some e := do `[simp only [add_coeff, mul_coeff, neg_coeff, sub_coeff, nsmul_coeff, zsmul_coeff, pow_coeff], apply eval₂_hom_congr' (ring_hom.ext_int _ _) _ rfl, rintro ⟨b, k⟩...
def
tactic.interactive.init_ring
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "finset.mem_product", "finset.mem_range", "finset.mem_univ", "matrix.cons_val_one", "matrix.cons_val_zero", "matrix.head_cons", "ring_hom.ext_int", "tactic.replace" ]
`init_ring` is an auxiliary tactic that discharges goals factoring `init` over ring operations.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
select (P : ℕ → Prop) (x : 𝕎 R) : 𝕎 R
mk p (λ n, if P n then x.coeff n else 0)
def
witt_vector.select
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
`witt_vector.select P x`, for a predicate `P : ℕ → Prop` is the Witt vector whose `n`-th coefficient is `x.coeff n` if `P n` is true, and `0` otherwise.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
select_poly (n : ℕ) : mv_polynomial ℕ ℤ
if P n then X n else 0
def
witt_vector.select_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "mv_polynomial" ]
The polynomial that witnesses that `witt_vector.select` is a polynomial function. `select_poly n` is `X n` if `P n` holds, and `0` otherwise.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_select (x : 𝕎 R) (n : ℕ) : (select P x).coeff n = aeval x.coeff (select_poly P n)
begin dsimp [select, select_poly], split_ifs with hi, { rw aeval_X }, { rw alg_hom.map_zero } end
lemma
witt_vector.coeff_select
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "alg_hom.map_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
select_is_poly (P : ℕ → Prop) : is_poly p (λ R _Rcr x, by exactI select P x)
begin use (select_poly P), rintro R _Rcr x, funext i, apply coeff_select end
lemma
witt_vector.select_is_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "is_poly" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
select_add_select_not : ∀ (x : 𝕎 R), select P x + select (λ i, ¬ P i) x = x
begin ghost_calc _, intro n, simp only [ring_hom.map_add], suffices : (bind₁ (select_poly P)) (witt_polynomial p ℤ n) + (bind₁ (select_poly (λ i, ¬P i))) (witt_polynomial p ℤ n) = witt_polynomial p ℤ n, { apply_fun (aeval x.coeff) at this, simpa only [alg_hom.map_add, aeval_bind₁, ← coeff_sel...
lemma
witt_vector.select_add_select_not
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "alg_hom.map_add", "alg_hom.map_mul", "alg_hom.map_pow", "alg_hom.map_sum", "ite_pow", "pow_pos", "ring_hom.map_add", "witt_polynomial", "witt_polynomial_eq_sum_C_mul_X_pow", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coeff_add_of_disjoint (x y : 𝕎 R) (h : ∀ n, x.coeff n = 0 ∨ y.coeff n = 0) : (x + y).coeff n = x.coeff n + y.coeff n
begin let P : ℕ → Prop := λ n, y.coeff n = 0, haveI : decidable_pred P := classical.dec_pred P, set z := mk p (λ n, if P n then x.coeff n else y.coeff n) with hz, have hx : select P z = x, { ext1 n, rw [select, coeff_mk, coeff_mk], split_ifs with hn, { refl }, { rw (h n).resolve_right hn } }, have hy : ...
lemma
witt_vector.coeff_add_of_disjoint
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "classical.dec_pred" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init (n : ℕ) : 𝕎 R → 𝕎 R
select (λ i, i < n)
def
witt_vector.init
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
`witt_vector.init n x` is the Witt vector of which the first `n` coefficients are those from `x` and all other coefficients are `0`. See `witt_vector.tail` for the complementary part.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
tail (n : ℕ) : 𝕎 R → 𝕎 R
select (λ i, n ≤ i)
def
witt_vector.tail
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
`witt_vector.tail n x` is the Witt vector of which the first `n` coefficients are `0` and all other coefficients are those from `x`. See `witt_vector.init` for the complementary part.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_add_tail (x : 𝕎 R) (n : ℕ) : init n x + tail n x = x
by simp only [init, tail, ← not_lt, select_add_select_not]
lemma
witt_vector.init_add_tail
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_init (x : 𝕎 R) (n : ℕ) : init n (init n x) = init n x
by init_ring
lemma
witt_vector.init_init
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_add (x y : 𝕎 R) (n : ℕ) : init n (x + y) = init n (init n x + init n y)
by init_ring using witt_add_vars
lemma
witt_vector.init_add
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_mul (x y : 𝕎 R) (n : ℕ) : init n (x * y) = init n (init n x * init n y)
by init_ring using witt_mul_vars
lemma
witt_vector.init_mul
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_neg (x : 𝕎 R) (n : ℕ) : init n (-x) = init n (-init n x)
by init_ring using witt_neg_vars
lemma
witt_vector.init_neg
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_sub (x y : 𝕎 R) (n : ℕ) : init n (x - y) = init n (init n x - init n y)
by init_ring using witt_sub_vars
lemma
witt_vector.init_sub
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_nsmul (m : ℕ) (x : 𝕎 R) (n : ℕ) : init n (m • x) = init n (m • init n x)
by init_ring using (λ p [fact (nat.prime p)] n, by exactI witt_nsmul_vars p m n)
lemma
witt_vector.init_nsmul
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "fact", "nat.prime" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_zsmul (m : ℤ) (x : 𝕎 R) (n : ℕ) : init n (m • x) = init n (m • init n x)
by init_ring using (λ p [fact (nat.prime p)] n, by exactI witt_zsmul_vars p m n)
lemma
witt_vector.init_zsmul
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "fact", "nat.prime" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_pow (m : ℕ) (x : 𝕎 R) (n : ℕ) : init n (x ^ m) = init n (init n x ^ m)
by init_ring using (λ p [fact (nat.prime p)] n, by exactI witt_pow_vars p m n)
lemma
witt_vector.init_pow
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "fact", "nat.prime" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
init_is_poly (n : ℕ) : is_poly p (λ R _Rcr, by exactI init n)
select_is_poly (λ i, i < n)
lemma
witt_vector.init_is_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/init_tail.lean
[ "ring_theory.witt_vector.basic", "ring_theory.witt_vector.is_poly" ]
[ "is_poly" ]
`witt_vector.init n x` is polynomial in the coefficients of `x`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
fraction_ring.frobenius : K(p, k) ≃+* K(p, k)
is_fraction_ring.field_equiv_of_ring_equiv (frobenius_equiv p k)
def
witt_vector.fraction_ring.frobenius
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[ "frobenius_equiv", "is_fraction_ring.field_equiv_of_ring_equiv" ]
The Frobenius automorphism of `k` induces an automorphism of `K`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
fraction_ring.frobenius_ring_hom : K(p, k) →+* K(p, k)
fraction_ring.frobenius p k
def
witt_vector.fraction_ring.frobenius_ring_hom
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[]
The Frobenius automorphism of `k` induces an endomorphism of `K`. For notation purposes.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inv_pair₁ : ring_hom_inv_pair (φ(p, k)) _
ring_hom_inv_pair.of_ring_equiv (fraction_ring.frobenius p k)
instance
witt_vector.inv_pair₁
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[ "ring_hom_inv_pair", "ring_hom_inv_pair.of_ring_equiv" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inv_pair₂ : ring_hom_inv_pair ((fraction_ring.frobenius p k).symm : K(p, k) →+* K(p, k)) _
ring_hom_inv_pair.of_ring_equiv (fraction_ring.frobenius p k).symm
instance
witt_vector.inv_pair₂
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[ "ring_hom_inv_pair", "ring_hom_inv_pair.of_ring_equiv" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
isocrystal (V : Type*) [add_comm_group V] extends module K(p, k) V
( frob : V ≃ᶠˡ[p, k] V )
class
witt_vector.isocrystal
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[ "add_comm_group", "module" ]
An isocrystal is a vector space over the field `K(p, k)` additionally equipped with a Frobenius-linear automorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
isocrystal.frobenius : V ≃ᶠˡ[p, k] V
@isocrystal.frob p _ k _ _ _ _ _ _ _
def
witt_vector.isocrystal.frobenius
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[]
Project the Frobenius automorphism from an isocrystal. Denoted by `Φ(p, k)` when V can be inferred.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
isocrystal_hom extends V →ₗ[K(p, k)] V₂
( frob_equivariant : ∀ x : V, Φ(p, k) (to_linear_map x) = to_linear_map (Φ(p, k) x) )
structure
witt_vector.isocrystal_hom
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[]
A homomorphism between isocrystals respects the Frobenius map.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
isocrystal_equiv extends V ≃ₗ[K(p, k)] V₂
( frob_equivariant : ∀ x : V, Φ(p, k) (to_linear_equiv x) = to_linear_equiv (Φ(p, k) x) )
structure
witt_vector.isocrystal_equiv
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[]
An isomorphism between isocrystals respects the Frobenius map.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
fraction_ring.module : module K(p, k) K(p, k)
semiring.to_module
def
witt_vector.fraction_ring.module
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[ "module", "semiring.to_module" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
standard_one_dim_isocrystal (m : ℤ) : Type*
K(p, k)
def
witt_vector.standard_one_dim_isocrystal
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[]
Type synonym for `K(p, k)` to carry the standard 1-dimensional isocrystal structure of slope `m : ℤ`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
standard_one_dim_isocrystal.frobenius_apply (m : ℤ) (x : standard_one_dim_isocrystal p k m) : Φ(p, k) x = (p:K(p, k)) ^ m • φ(p, k) x
rfl
lemma
witt_vector.standard_one_dim_isocrystal.frobenius_apply
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
isocrystal_classification (k : Type*) [field k] [is_alg_closed k] [char_p k p] (V : Type*) [add_comm_group V] [isocrystal p k V] (h_dim : finrank K(p, k) V = 1) : ∃ (m : ℤ), nonempty (standard_one_dim_isocrystal p k m ≃ᶠⁱ[p, k] V)
begin haveI : nontrivial V := finite_dimensional.nontrivial_of_finrank_eq_succ h_dim, obtain ⟨x, hx⟩ : ∃ x : V, x ≠ 0 := exists_ne 0, have : Φ(p, k) x ≠ 0 := by simpa only [map_zero] using Φ(p,k).injective.ne hx, obtain ⟨a, ha, hax⟩ : ∃ a : K(p, k), a ≠ 0 ∧ Φ(p, k) x = a • x, { rw finrank_eq_one_iff_of_nonzer...
theorem
witt_vector.isocrystal_classification
ring_theory.witt_vector
src/ring_theory/witt_vector/isocrystal.lean
[ "ring_theory.witt_vector.frobenius_fraction_field" ]
[ "add_comm_group", "algebra.id.smul_eq_mul", "char_p", "exists_ne", "field", "finite_dimensional.nontrivial_of_finrank_eq_succ", "finrank_eq_one_iff_of_nonzero", "finrank_eq_one_iff_of_nonzero'", "is_alg_closed", "linear_equiv.map_smul", "linear_equiv.map_smulₛₗ", "linear_equiv.of_bijective", ...
A one-dimensional isocrystal over an algebraically closed field admits an isomorphism to one of the standard (indexed by `m : ℤ`) one-dimensional isocrystals.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ghost_simp (lems : parse simp_arg_list) : tactic unit
do tactic.try tactic.intro1, simp none none tt (lems ++ [simp_arg_type.symm_expr ``(sub_eq_add_neg)]) [`ghost_simps] (loc.ns [none])
def
tactic.interactive.ghost_simp
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[]
A macro for a common simplification when rewriting with ghost component equations.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ghost_calc (ids' : parse ident_*) : tactic unit
do ids ← ids'.mmap $ λ n, get_local n <|> tactic.intro n, `(@eq (witt_vector _ %%R) _ _) ← target, match ids with | [x] := refine ```(is_poly.ext _ _ _ _ %%x) | [x, y] := refine ```(is_poly₂.ext _ _ _ _ %%x %%y) | _ := fail "ghost_calc takes one or two arguments" end, nm ← match R with | expr.lo...
def
tactic.interactive.ghost_calc
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "tactic.clear'" ]
`ghost_calc` is a tactic for proving identities between polynomial functions. Typically, when faced with a goal like ```lean ∀ (x y : 𝕎 R), verschiebung (x * frobenius y) = verschiebung x * y ``` you can 1. call `ghost_calc` 2. do a small amount of manual work -- maybe nothing, maybe `rintro`, etc 3. call `ghost_simp`...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
poly_eq_of_witt_polynomial_bind_eq' (f g : ℕ → mv_polynomial (idx × ℕ) ℤ) (h : ∀ n, bind₁ f (witt_polynomial p _ n) = bind₁ g (witt_polynomial p _ n)) : f = g
begin ext1 n, apply mv_polynomial.map_injective (int.cast_ring_hom ℚ) int.cast_injective, rw ← function.funext_iff at h, replace h := congr_arg (λ fam, bind₁ (mv_polynomial.map (int.cast_ring_hom ℚ) ∘ fam) (X_in_terms_of_W p ℚ n)) h, simpa only [function.comp, map_bind₁, map_witt_polynomial, ← bin...
lemma
witt_vector.poly_eq_of_witt_polynomial_bind_eq'
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "X_in_terms_of_W", "bind₁_witt_polynomial_X_in_terms_of_W", "function.funext_iff", "int.cast_injective", "int.cast_ring_hom", "map_witt_polynomial", "mv_polynomial", "mv_polynomial.map", "mv_polynomial.map_injective", "witt_polynomial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
poly_eq_of_witt_polynomial_bind_eq (f g : ℕ → mv_polynomial ℕ ℤ) (h : ∀ n, bind₁ f (witt_polynomial p _ n) = bind₁ g (witt_polynomial p _ n)) : f = g
begin ext1 n, apply mv_polynomial.map_injective (int.cast_ring_hom ℚ) int.cast_injective, rw ← function.funext_iff at h, replace h := congr_arg (λ fam, bind₁ (mv_polynomial.map (int.cast_ring_hom ℚ) ∘ fam) (X_in_terms_of_W p ℚ n)) h, simpa only [function.comp, map_bind₁, map_witt_polynomial, ← bin...
lemma
witt_vector.poly_eq_of_witt_polynomial_bind_eq
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "X_in_terms_of_W", "bind₁_witt_polynomial_X_in_terms_of_W", "function.funext_iff", "int.cast_injective", "int.cast_ring_hom", "map_witt_polynomial", "mv_polynomial", "mv_polynomial.map", "mv_polynomial.map_injective", "witt_polynomial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_poly (f : Π ⦃R⦄ [comm_ring R], witt_vector p R → 𝕎 R) : Prop
mk' :: (poly : ∃ φ : ℕ → mv_polynomial ℕ ℤ, ∀ ⦃R⦄ [comm_ring R] (x : 𝕎 R), by exactI (f x).coeff = λ n, aeval x.coeff (φ n))
class
witt_vector.is_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "comm_ring", "is_poly", "mk'", "mv_polynomial", "poly", "witt_vector" ]
A function `f : Π R, 𝕎 R → 𝕎 R` that maps Witt vectors to Witt vectors over arbitrary base rings is said to be *polynomial* if there is a family of polynomials `φₙ` over `ℤ` such that the `n`th coefficient of `f x` is given by evaluating `φₙ` at the coefficients of `x`. See also `witt_vector.is_poly₂` for the binary...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id_is_poly : is_poly p (λ _ _, id)
⟨⟨X, by { introsI, simp only [aeval_X, id] }⟩⟩
instance
witt_vector.id_is_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly" ]
The identity function on Witt vectors is a polynomial function.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
id_is_poly_i' : is_poly p (λ _ _ a, a)
witt_vector.id_is_poly _
instance
witt_vector.id_is_poly_i'
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly", "witt_vector.id_is_poly" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ext {f g} (hf : is_poly p f) (hg : is_poly p g) (h : ∀ (R : Type u) [_Rcr : comm_ring R] (x : 𝕎 R) (n : ℕ), by exactI ghost_component n (f x) = ghost_component n (g x)) : ∀ (R : Type u) [_Rcr : comm_ring R] (x : 𝕎 R), by exactI f x = g x
begin unfreezingI { obtain ⟨φ, hf⟩ := hf, obtain ⟨ψ, hg⟩ := hg }, intros, ext n, rw [hf, hg, poly_eq_of_witt_polynomial_bind_eq p φ ψ], intro k, apply mv_polynomial.funext, intro x, simp only [hom_bind₁], specialize h (ulift ℤ) (mk p $ λ i, ⟨x i⟩) k, simp only [ghost_component_apply, aeval_eq_...
lemma
witt_vector.is_poly.ext
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "comm_ring", "is_poly", "mv_polynomial.eval", "mv_polynomial.funext", "ring_hom.ext_int" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp {g f} (hg : is_poly p g) (hf : is_poly p f) : is_poly p (λ R _Rcr, @g R _Rcr ∘ @f R _Rcr)
begin unfreezingI { obtain ⟨φ, hf⟩ := hf, obtain ⟨ψ, hg⟩ := hg }, use (λ n, bind₁ φ (ψ n)), intros, simp only [aeval_bind₁, function.comp, hg, hf] end
lemma
witt_vector.is_poly.comp
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly" ]
The composition of polynomial functions is polynomial.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_poly₂ (f : Π ⦃R⦄ [comm_ring R], witt_vector p R → 𝕎 R → 𝕎 R) : Prop
mk' :: (poly : ∃ φ : ℕ → mv_polynomial (fin 2 × ℕ) ℤ, ∀ ⦃R⦄ [comm_ring R] (x y : 𝕎 R), by exactI (f x y).coeff = λ n, peval (φ n) ![x.coeff, y.coeff])
class
witt_vector.is_poly₂
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "comm_ring", "mk'", "mv_polynomial", "poly", "witt_vector" ]
A binary function `f : Π R, 𝕎 R → 𝕎 R → 𝕎 R` on Witt vectors is said to be *polynomial* if there is a family of polynomials `φₙ` over `ℤ` such that the `n`th coefficient of `f x y` is given by evaluating `φₙ` at the coefficients of `x` and `y`. See also `witt_vector.is_poly` for the unary variant. The `ghost_calc`...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_poly₂.comp {h f g} (hh : is_poly₂ p h) (hf : is_poly p f) (hg : is_poly p g) : is_poly₂ p (λ R _Rcr x y, by exactI h (f x) (g y))
begin unfreezingI { obtain ⟨φ, hf⟩ := hf, obtain ⟨ψ, hg⟩ := hg, obtain ⟨χ, hh⟩ := hh }, refine ⟨⟨(λ n, bind₁ (uncurry $ ![λ k, rename (prod.mk (0 : fin 2)) (φ k), λ k, rename (prod.mk (1 : fin 2)) (ψ k)]) (χ n)), _⟩⟩, intros, funext n, simp only [peval, aeval_bind₁, function.co...
lemma
witt_vector.is_poly₂.comp
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly", "matrix.cons_val_one", "matrix.cons_val_zero", "matrix.head_cons" ]
The composition of polynomial functions is polynomial.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_poly.comp₂ {g f} (hg : is_poly p g) (hf : is_poly₂ p f) : is_poly₂ p (λ R _Rcr x y, by exactI g (f x y))
begin unfreezingI { obtain ⟨φ, hf⟩ := hf, obtain ⟨ψ, hg⟩ := hg }, use (λ n, bind₁ φ (ψ n)), intros, simp only [peval, aeval_bind₁, function.comp, hg, hf] end
lemma
witt_vector.is_poly.comp₂
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly" ]
The composition of a polynomial function with a binary polynomial function is polynomial.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_poly₂.diag {f} (hf : is_poly₂ p f) : is_poly p (λ R _Rcr x, by exactI f x x)
begin unfreezingI {obtain ⟨φ, hf⟩ := hf}, refine ⟨⟨λ n, bind₁ (uncurry ![X, X]) (φ n), _⟩⟩, intros, funext n, simp only [hf, peval, uncurry, aeval_bind₁], apply eval₂_hom_congr rfl _ rfl, ext ⟨i, k⟩, fin_cases i; simp only [matrix.head_cons, aeval_X, matrix.cons_val_zero, matrix.cons_val_one], end
lemma
witt_vector.is_poly₂.diag
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly", "matrix.cons_val_one", "matrix.cons_val_zero", "matrix.head_cons" ]
The diagonal `λ x, f x x` of a polynomial function `f` is polynomial.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk_poly_comp_lemmas (n : name) (vars : list expr) (p : expr) : tactic unit
do c ← mk_const n, let appd := vars.foldl expr.app c, tgt_bod ← to_expr ``(λ f [hf : is_poly %%p f], is_poly.comp %%appd hf) >>= replace_univ_metas_with_univ_params, tgt_bod ← lambdas vars tgt_bod, tgt_tp ← infer_type tgt_bod, let nm := n <.> "comp_i", add_decl $ mk_definition nm tgt_tp.collect_...
def
witt_vector.tactic.mk_poly_comp_lemmas
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "set_attribute" ]
If `n` is the name of a lemma with opened type `∀ vars, is_poly p _`, `mk_poly_comp_lemmas n vars p` adds composition instances to the environment `n.comp_i` and `n.comp₂_i`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk_poly₂_comp_lemmas (n : name) (vars : list expr) (p : expr) : tactic unit
do c ← mk_const n, let appd := vars.foldl expr.app c, tgt_bod ← to_expr ``(λ {f g} [hf : is_poly %%p f] [hg : is_poly %%p g], is_poly₂.comp %%appd hf hg) >>= replace_univ_metas_with_univ_params, tgt_bod ← lambdas vars tgt_bod, tgt_tp ← infer_type tgt_bod >>= simp_lemmas.mk.dsimplify, let nm := n <....
def
witt_vector.tactic.mk_poly₂_comp_lemmas
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "set_attribute" ]
If `n` is the name of a lemma with opened type `∀ vars, is_poly₂ p _`, `mk_poly₂_comp_lemmas n vars p` adds composition instances to the environment `n.comp₂_i` and `n.comp_diag`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mk_comp_lemmas (n : name) : tactic unit
do d ← get_decl n, (vars, tp) ← open_pis d.type, match tp with | `(is_poly %%p _) := mk_poly_comp_lemmas n vars p | `(is_poly₂ %%p _) := mk_poly₂_comp_lemmas n vars p | _ := fail "@[is_poly] should only be applied to terms of type `is_poly _ _` or `is_poly₂ _ _`" end
def
witt_vector.tactic.mk_comp_lemmas
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[]
The `after_set` function for `@[is_poly]`. Calls `mk_poly(₂)_comp_lemmas`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_poly_attr : user_attribute
{ name := `is_poly, descr := "Lemmas with this attribute describe the polynomial structure of functions", after_set := some $ λ n _ _, mk_comp_lemmas n }
def
witt_vector.tactic.is_poly_attr
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly" ]
`@[is_poly]` is applied to lemmas of the form `is_poly f φ` or `is_poly₂ f φ`. These lemmas should *not* be tagged as instances, and only atomic `is_poly` defs should be tagged: composition lemmas should not. Roughly speaking, lemmas that take `is_poly` proofs as arguments should not be tagged. Type class inference st...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
neg_is_poly : is_poly p (λ R _, by exactI @has_neg.neg (𝕎 R) _)
⟨⟨λ n, rename prod.snd (witt_neg p n), begin introsI, funext n, rw [neg_coeff, aeval_eq_eval₂_hom, eval₂_hom_rename], apply eval₂_hom_congr rfl _ rfl, ext ⟨i, k⟩, fin_cases i, refl, end⟩⟩
lemma
witt_vector.neg_is_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly" ]
The additive negation is a polynomial function on Witt vectors.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
zero_is_poly : is_poly p (λ _ _ _, by exactI 0)
⟨⟨0, by { introsI, funext n, simp only [pi.zero_apply, alg_hom.map_zero, zero_coeff] }⟩⟩
instance
witt_vector.zero_is_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "alg_hom.map_zero", "is_poly" ]
The function that is constantly zero on Witt vectors is a polynomial function.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
bind₁_zero_witt_polynomial (n : ℕ) : bind₁ (0 : ℕ → mv_polynomial ℕ R) (witt_polynomial p R n) = 0
by rw [← aeval_eq_bind₁, aeval_zero, constant_coeff_witt_polynomial, ring_hom.map_zero]
lemma
witt_vector.bind₁_zero_witt_polynomial
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "constant_coeff_witt_polynomial", "mv_polynomial", "ring_hom.map_zero", "witt_polynomial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
one_poly (n : ℕ) : mv_polynomial ℕ ℤ
if n = 0 then 1 else 0
def
witt_vector.one_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "mv_polynomial" ]
The coefficients of `1 : 𝕎 R` as polynomials.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
bind₁_one_poly_witt_polynomial (n : ℕ) : bind₁ one_poly (witt_polynomial p ℤ n) = 1
begin rw [witt_polynomial_eq_sum_C_mul_X_pow, alg_hom.map_sum, finset.sum_eq_single 0], { simp only [one_poly, one_pow, one_mul, alg_hom.map_pow, C_1, pow_zero, bind₁_X_right, if_true, eq_self_iff_true], }, { intros i hi hi0, simp only [one_poly, if_neg hi0, zero_pow (pow_pos hp.1.pos _), mul_zero, ...
lemma
witt_vector.bind₁_one_poly_witt_polynomial
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "alg_hom.map_mul", "alg_hom.map_pow", "alg_hom.map_sum", "finset.mem_range", "mul_zero", "one_mul", "one_pow", "pow_pos", "pow_zero", "witt_polynomial", "witt_polynomial_eq_sum_C_mul_X_pow", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
one_is_poly : is_poly p (λ _ _ _, by exactI 1)
⟨⟨one_poly, begin introsI, funext n, cases n, { simp only [one_poly, if_true, eq_self_iff_true, one_coeff_zero, alg_hom.map_one], }, { simp only [one_poly, nat.succ_pos', one_coeff_eq_of_pos, if_neg n.succ_ne_zero, alg_hom.map_zero] } end⟩⟩
instance
witt_vector.one_is_poly
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "alg_hom.map_one", "alg_hom.map_zero", "is_poly", "nat.succ_pos'" ]
The function that is constantly one on Witt vectors is a polynomial function.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_is_poly₂ [fact p.prime] : is_poly₂ p (λ _ _, by exactI (+))
⟨⟨witt_add p, by { introsI, dunfold witt_vector.has_add, simp [eval] }⟩⟩
lemma
witt_vector.add_is_poly₂
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "fact" ]
Addition of Witt vectors is a polynomial function.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_is_poly₂ [fact p.prime] : is_poly₂ p (λ _ _, by exactI (*))
⟨⟨witt_mul p, by { introsI, dunfold witt_vector.has_mul, simp [eval] }⟩⟩
lemma
witt_vector.mul_is_poly₂
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "fact" ]
Multiplication of Witt vectors is a polynomial function.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_poly.map {f} (hf : is_poly p f) (g : R →+* S) (x : 𝕎 R) : map g (f x) = f (map g x)
begin -- this could be turned into a tactic “macro” (taking `hf` as parameter) -- so that applications do not have to worry about the universe issue -- see `is_poly₂.map` for a slightly more general proof strategy unfreezingI {obtain ⟨φ, hf⟩ := hf}, ext n, simp only [map_coeff, hf, map_aeval], apply eval₂...
lemma
witt_vector.is_poly.map
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly", "ring_hom.ext_int" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_left {g f} (hg : is_poly₂ p g) (hf : is_poly p f) : is_poly₂ p (λ R _Rcr x y, by exactI g (f x) y)
hg.comp hf (witt_vector.id_is_poly _)
lemma
witt_vector.is_poly₂.comp_left
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly", "witt_vector.id_is_poly" ]
The composition of a binary polynomial function with a unary polynomial function in the first argument is polynomial.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_right {g f} (hg : is_poly₂ p g) (hf : is_poly p f) : is_poly₂ p (λ R _Rcr x y, by exactI g x (f y))
hg.comp (witt_vector.id_is_poly p) hf
lemma
witt_vector.is_poly₂.comp_right
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "is_poly", "witt_vector.id_is_poly" ]
The composition of a binary polynomial function with a unary polynomial function in the second argument is polynomial.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ext {f g} (hf : is_poly₂ p f) (hg : is_poly₂ p g) (h : ∀ (R : Type u) [_Rcr : comm_ring R] (x y : 𝕎 R) (n : ℕ), by exactI ghost_component n (f x y) = ghost_component n (g x y)) : ∀ (R) [_Rcr : comm_ring R] (x y : 𝕎 R), by exactI f x y = g x y
begin unfreezingI { obtain ⟨φ, hf⟩ := hf, obtain ⟨ψ, hg⟩ := hg }, intros, ext n, rw [hf, hg, poly_eq_of_witt_polynomial_bind_eq' p φ ψ], clear x y, intro k, apply mv_polynomial.funext, intro x, simp only [hom_bind₁], specialize h (ulift ℤ) (mk p $ λ i, ⟨x (0, i)⟩) (mk p $ λ i, ⟨x (1, i)⟩) k, ...
lemma
witt_vector.is_poly₂.ext
ring_theory.witt_vector
src/ring_theory/witt_vector/is_poly.lean
[ "algebra.ring.ulift", "ring_theory.witt_vector.basic", "data.mv_polynomial.funext" ]
[ "comm_ring", "mv_polynomial.eval", "mv_polynomial.funext", "ring_hom.ext_int" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83