refactor,feat(library/{data,algebra}): move bigops to algebra, define sums

library/algebra/algebra.md

@@ -8,6 +8,8 @@ Algebraic structures.
 * [binary](binary.lean) : binary operations
 * [wf](wf.lean) : well-founded relations
 * [group](group.lean)
+* [group_power](group_power.lean) : nat and int powers
+* [group_bigops](group_bigops.lean) : finite products and sums
 * [ring](ring.lean)
 * [ordered_group](ordered_group.lean)
 * [ordered_ring](ordered_ring.lean)

library/algebra/group_bigops.lean

@@ -0,0 +1,229 @@
+/-
+Copyright (c) 2015 Jeremy Avigad. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura, Jeremy Avigad
+
+Finite products on a monoid, and finite sums on an additive monoid. These are called
+
+  algebra.list.prod
+  algebra.finset.prod
+  algebra.list.sum
+  algebra.finset.sum
+
+So when we open algebra we have list.prod etc., and when we migrate to nat, we have
+nat.list.prod etc.
+
+We have to be careful with dependencies. This theory imports files from finset and list, which
+import basic files from nat. Then nat imports this file to instantiate finite products and sums.
+-/
+import .group data.list.basic data.list.perm data.finset.basic
+open algebra function binary quot subtype
+
+namespace algebra
+
+/- list.prod -/
+
+namespace list -- i.e. algebra.list
+  open list    -- i.e. ordinary lists
+
+  variable {A : Type}
+
+  section monoid
+  variables {B : Type} [mB : monoid B]
+  include mB
+
+  definition mulf (f : A → B) : B → A → B :=
+  λ b a, b * f a
+
+  definition prod (l : list A) (f : A → B) : B :=
+  list.foldl (mulf f) 1 l
+
+  -- ∏ x ← l, f x
+  notation `∏` binders `←` l, r:(scoped f, prod l f) := r
+
+  private theorem foldl_const (f : A → B) :
+    ∀ (l : list A) (b : B), foldl (mulf f) b l = b * foldl (mulf f) 1 l
+  | []     b := by rewrite [*foldl_nil, mul_one]
+  | (a::l) b := by rewrite [*foldl_cons, foldl_const, {foldl _ (mulf f 1 a) _}foldl_const, ↑mulf,
+                             one_mul, mul.assoc]
+
+  theorem prod_nil (f : A → B) : prod [] f = 1 := rfl
+
+  theorem prod_cons (f : A → B) (a : A) (l : list A) : prod (a::l) f = f a * prod l f :=
+  by rewrite [↑prod, foldl_cons, foldl_const, ↑mulf, one_mul]
+
+  theorem prod_append :
+    ∀ (l₁ l₂ : list A) (f : A → B), prod (l₁++l₂) f = prod l₁ f * prod l₂ f
+  | []    l₂ f  := by rewrite [append_nil_left, prod_nil, one_mul]
+  | (a::l) l₂ f := by rewrite [append_cons, *prod_cons, prod_append, mul.assoc]
+
+  section decidable_eq
+  variable [H : decidable_eq A]
+  include H
+
+  theorem prod_insert_of_mem (f : A → B) {a : A} {l : list A} : a ∈ l →
+    prod (insert a l) f = prod l f :=
+  assume ainl, by rewrite [insert_eq_of_mem ainl]
+
+  theorem prod_insert_of_not_mem (f : A → B) {a : A} {l : list A} :
+    a ∉ l → prod (insert a l) f = f a * prod l f :=
+  assume nainl, by rewrite [insert_eq_of_not_mem nainl, prod_cons]
+
+  theorem prod_union {l₁ l₂ : list A} (f : A → B) (d : disjoint l₁ l₂) :
+    prod (union l₁ l₂) f = prod l₁ f * prod l₂ f :=
+  by rewrite [union_eq_append d, prod_append]
+
+  end decidable_eq
+  end monoid
+
+  section comm_monoid
+  variables {B : Type} [cmB : comm_monoid B]
+  include cmB
+
+  theorem prod_mul (l : list A) (f g : A → B) : prod l (λx, f x * g x) = prod l f * prod l g :=
+  list.induction_on l
+     (by rewrite [*prod_nil, mul_one])
+     (take a l,
+       assume IH,
+       by rewrite [*prod_cons, IH, *mul.assoc, mul.left_comm (prod l f)])
+
+  end comm_monoid
+end list
+
+/- finset.prod -/
+
+namespace finset
+  open finset
+  variables {A B : Type}
+  variable [cmB : comm_monoid B]
+  include cmB
+
+  theorem mulf_rcomm (f : A → B) : right_commutative (list.mulf f) :=
+  right_commutative_compose_right (@has_mul.mul B cmB) f (@mul.right_comm B cmB)
+
+  section
+  open perm
+  theorem listprod_of_perm (f : A → B) {l₁ l₂ : list A} :
+    l₁ ~ l₂ → list.prod l₁ f = list.prod l₂ f :=
+  λ p, foldl_eq_of_perm (mulf_rcomm f) p 1
+  end
+
+  definition prod (s : finset A) (f : A → B) : B :=
+  quot.lift_on s
+  (λ l, list.prod (elt_of l) f)
+  (λ l₁ l₂ p, listprod_of_perm f p)
+
+  -- ∏ x ∈ s, f x
+  notation `∏` binders `∈` s, r:(scoped f, prod s f) := r
+
+  theorem prod_empty (f : A → B) : prod ∅ f = 1 :=
+  list.prod_nil f
+
+  section decidable_eq
+  variable [H : decidable_eq A]
+  include H
+
+  theorem prod_insert_of_mem (f : A → B) {a : A} {s : finset A} :
+    a ∈ s → prod (insert a s) f = prod s f :=
+  quot.induction_on s
+    (λ l ainl, list.prod_insert_of_mem f ainl)
+
+  theorem prod_insert_of_not_mem (f : A → B) {a : A} {s : finset A} :
+    a ∉ s → prod (insert a s) f = f a * prod s f :=
+  quot.induction_on s
+    (λ l nainl, list.prod_insert_of_not_mem f nainl)
+
+  theorem prod_union (f : A → B) {s₁ s₂ : finset A} (disj : s₁ ∩ s₂ = ∅) :
+    prod (s₁ ∪ s₂) f = prod s₁ f * prod s₂ f :=
+  have H1 : disjoint s₁ s₂ → prod (s₁ ∪ s₂) f = prod s₁ f * prod s₂ f, from
+    quot.induction_on₂ s₁ s₂
+      (λ l₁ l₂ d, list.prod_union f d),
+  H1 (disjoint_of_inter_empty disj)
+
+  theorem prod_mul (s : finset A) (f g : A → B) : prod s (λx, f x * g x) = prod s f * prod s g :=
+  quot.induction_on s (take u, !list.prod_mul)
+
+  end decidable_eq
+end finset
+
+/- list.sum -/
+
+namespace list
+  open list
+  variable {A : Type}
+
+  section add_monoid
+  variables {B : Type} [amB : add_monoid B]
+  include amB
+  local attribute add_monoid.to_monoid [instance]
+
+  definition sum (l : list A) (f : A → B) : B := prod l f
+
+  -- ∑ x ← l, f x
+  notation `∑` binders `←` l, r:(scoped f, sum l f) := r
+
+  theorem sum_nil (f : A → B) : sum [] f = 0 := prod_nil f
+  theorem sum_cons (f : A → B) (a : A) (l : list A) : sum (a::l) f = f a + sum l f :=
+    prod_cons f a l
+  theorem sum_append (l₁ l₂ : list A) (f : A → B) : sum (l₁++l₂) f = sum l₁ f + sum l₂ f :=
+    prod_append l₁ l₂ f
+
+  section decidable_eq
+  variable [H : decidable_eq A]
+  include H
+
+  theorem sum_insert_of_mem (f : A → B) {a : A} {l : list A} (H : a ∈ l) :
+    sum (insert a l) f = sum l f := prod_insert_of_mem f H
+  theorem sum_insert_of_not_mem (f : A → B) {a : A} {l : list A} (H : a ∉ l) :
+    sum (insert a l) f = f a * sum l f := prod_insert_of_not_mem f H
+  theorem sum_union {l₁ l₂ : list A} (f : A → B) (d : disjoint l₁ l₂) :
+    sum (union l₁ l₂) f = sum l₁ f + sum l₂ f := prod_union f d
+  end decidable_eq
+  end add_monoid
+
+  section add_comm_monoid
+  variables {B : Type} [acmB : add_comm_monoid B]
+  include acmB
+  local attribute add_comm_monoid.to_comm_monoid [instance]
+
+  theorem sum_add (l : list A) (f g : A → B) : sum l (λx, f x + g x) = sum l f + sum l g :=
+    prod_mul l f g
+  end add_comm_monoid
+end list
+
+/- finset.sum -/
+
+namespace finset
+  open finset
+  variable {A : Type}
+
+  section add_comm_monoid
+  variables {B : Type} [acmB : add_comm_monoid B]
+  include acmB
+  local attribute add_comm_monoid.to_comm_monoid [instance]
+
+  definition sum (s : finset A) (f : A → B) : B := prod s f
+
+  -- ∑ x ∈ s, f x
+  notation `∑` binders `∈` s, r:(scoped f, sum s f) := r
+
+  theorem sum_empty (f : A → B) : sum ∅ f = 0 := prod_empty f
+
+  section decidable_eq
+  variable [H : decidable_eq A]
+  include H
+
+  theorem sum_insert_of_mem (f : A → B) {a : A} {s : finset A} (H : a ∈ s) :
+    sum (insert a s) f = sum s f := prod_insert_of_mem f H
+  theorem sum_insert_of_not_mem (f : A → B) {a : A} {s : finset A} (H : a ∉ s) :
+    sum (insert a s) f = f a + sum s f := prod_insert_of_not_mem f H
+  theorem sum_union (f : A → B) {s₁ s₂ : finset A} (disj : s₁ ∩ s₂ = ∅) :
+    sum (s₁ ∪ s₂) f = sum s₁ f + sum s₂ f := prod_union f disj
+  theorem sum_add (s : finset A) (f g : A → B) :
+    sum s (λx, f x + g x) = sum s f + sum s g := prod_mul s f g
+
+  end decidable_eq
+  end add_comm_monoid
+end finset
+
+end algebra

library/data/finset/bigop.lean

@@ -1,41 +0,0 @@
-/-
-Copyright (c) 2015 Microsoft Corporation. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Author: Leonardo de Moura
-
-Big operator for finite sets.
--/
-import algebra.group data.finset.basic data.list.bigop
-open algebra finset function binary quot subtype
-
-namespace finset
-variables {A B : Type}
-variable  [g : comm_monoid B]
-include g
-
-definition bigop (s : finset A) (f : A → B) : B :=
-quot.lift_on s
-  (λ l, list.bigop (elt_of l) f)
-  (λ l₁ l₂ p, list.bigop_of_perm f p)
-
-theorem bigop_empty (f : A → B) : bigop ∅ f = 1 :=
-list.bigop_nil f
-
-variable [H : decidable_eq A]
-include H
-
-theorem bigop_insert_of_mem (f : A → B) {a : A} {s : finset A} : a ∈ s → bigop (insert a s) f = bigop s f :=
-quot.induction_on s
-  (λ l ainl, list.bigop_insert_of_mem f ainl)
-
-theorem bigop_insert_of_not_mem (f : A → B) {a : A} {s : finset A} : a ∉ s → bigop (insert a s) f = f a * bigop s f :=
-quot.induction_on s
-  (λ l nainl, list.bigop_insert_of_not_mem f nainl)
-
-theorem bigop_union (f : A → B) {s₁ s₂ : finset A} (disj : s₁ ∩ s₂ = ∅) :
-bigop (s₁ ∪ s₂) f = bigop s₁ f * bigop s₂ f :=
-have H1 : disjoint s₁ s₂ → bigop (s₁ ∪ s₂) f = bigop s₁ f * bigop s₂ f, from
-  quot.induction_on₂ s₁ s₂
-    (λ l₁ l₂ d, list.bigop_union f d),
-H1 (disjoint_of_inter_empty disj)
-end finset

library/data/finset/default.lean

@@ -5,4 +5,4 @@ Author: Leonardo de Moura
 
 Finite sets.
 -/
-import data.finset.basic data.finset.comb data.finset.card data.finset.bigop
+import .basic .comb .to_set .card

library/data/finset/finset.md

@@ -5,5 +5,5 @@ Finite sets. By default, `import list` imports everything here.
 
 [basic](basic.lean) : basic operations and properties
 [comb](comb.lean) : combinators and list constructions
+[to_set](to_set.lean) : interactions with sets
 [card](card.lean) : cardinality
-[bigop](bigop.lean) : "big" operations

library/data/list/bigop.lean

@@ -1,69 +0,0 @@
-/-
-Copyright (c) 2015 Leonardo de Moura. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-
-Module: data.list.bigop
-Authors: Leonardo de Moura
-
-Big operator for lists
--/
-import algebra.group data.list.comb data.list.set data.list.perm
-open algebra function binary quot
-
-namespace list
-variables {A B : Type}
-variable  [g : monoid B]
-include g
-
-definition mulf (f : A → B) : B → A → B :=
-λ b a, b * f a
-
-definition bigop (l : list A) (f : A → B) : B :=
-foldl (mulf f) 1 l
-
-private theorem foldl_const (f : A → B) : ∀ (l : list A) (b : B), foldl (mulf f) b l = b * foldl (mulf f) 1 l
-| []     b := by rewrite [*foldl_nil, mul_one]
-| (a::l) b := by rewrite [*foldl_cons, foldl_const, {foldl _ (mulf f 1 a) _}foldl_const, ↑mulf, one_mul, mul.assoc]
-
-theorem bigop_nil (f : A → B) : bigop [] f = 1 :=
-rfl
-
-theorem bigop_cons (f : A → B) (a : A) (l : list A) : bigop (a::l) f = f a * bigop l f :=
-by rewrite [↑bigop, foldl_cons, foldl_const, ↑mulf, one_mul]
-
-theorem bigop_append : ∀ (l₁ l₂ : list A) (f : A → B), bigop (l₁++l₂) f = bigop l₁ f * bigop l₂ f
-| []    l₂ f  := by rewrite [append_nil_left, bigop_nil, one_mul]
-| (a::l) l₂ f := by rewrite [append_cons, *bigop_cons, bigop_append, mul.assoc]
-
-section insert
-variable [H : decidable_eq A]
-include H
-
-theorem bigop_insert_of_mem (f : A → B) {a : A} {l : list A} : a ∈ l → bigop (insert a l) f = bigop l f :=
-assume ainl, by rewrite [insert_eq_of_mem ainl]
-
-theorem bigop_insert_of_not_mem (f : A → B) {a : A} {l : list A} : a ∉ l → bigop (insert a l) f = f a * bigop l f :=
-assume nainl, by rewrite [insert_eq_of_not_mem nainl, bigop_cons]
-end insert
-
-section union
-variable [H : decidable_eq A]
-include H
-
-definition bigop_union {l₁ l₂ : list A} (f : A → B) (d : disjoint l₁ l₂) : bigop (union l₁ l₂) f = bigop l₁ f * bigop l₂ f :=
-by rewrite [union_eq_append d, bigop_append]
-end union
-end list
-
-namespace list
-open perm
-variables {A B : Type}
-variable  [g : comm_monoid B]
-include g
-
-theorem mulf_rcomm (f : A → B) : right_commutative (mulf f) :=
-right_commutative_compose_right (@has_mul.mul B g) f (@mul.right_comm B g)
-
-theorem bigop_of_perm (f : A → B) {l₁ l₂ : list A} : l₁ ~ l₂ → bigop l₁ f = bigop l₂ f :=
-λ p, foldl_eq_of_perm (mulf_rcomm f) p 1
-end list

library/data/list/default.lean

@@ -3,5 +3,4 @@ Copyright (c) 2014 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Author: Jeremy Avigad
 -/
-import data.list.basic data.list.comb data.list.set data.list.perm
+import .basic .comb .set .perm .as_type
-import data.list.bigop data.list.as_type

library/data/list/list.md

@@ -7,5 +7,4 @@ List of elements of a fixed type. By default, `import list` imports everything h
 [comb](comb.lean) : combinators and list constructions
 [set](set.lean) : set-like operations (these support the finset construction)
 [perm](perm.lean) : equivalence up to permutation (these support the finset construction)
-[bigop](bigop.lean) : "big" operations
 [as_type](as_type.lean) : treats a list as a type

library/data/nat/nat.md

@@ -8,3 +8,5 @@ The natural numbers.
 * [bquant](bquant.lean) : bounded quantifiers
 * [sub](sub.lean) : subtraction, and distance
 * [div](div.lean) : div, mod, gcd, and lcm
+* [power](power.lean)
+* [bigops](bigops.lean) : finite sums and products

library/data/nat/power.lean

@@ -5,7 +5,7 @@ Authors: Leonardo de Moura, Jeremy Avigad
 
 The power function on the natural numbers.
 -/
-import data.nat.basic data.nat.order data.nat.div algebra.group_pow
+import data.nat.basic data.nat.order data.nat.div algebra.group_power
 
 namespace nat