(* Definition 2.4 *)
definition upper_bound ≝ λO:ordered_set.λa:sequence O.λu:O.∀n:nat.a n ≤ u.
+definition lower_bound ≝ λO:ordered_set.λa:sequence O.λu:O.∀n:nat.u ≤ a n.
definition supremum ≝
λO:ordered_set.λs:sequence O.λx.upper_bound ? s x ∧ (∀y:O.x ≰ y → ∃n.s n ≰ y).
+definition infimum ≝
+ λO:ordered_set.λs:sequence O.λx.lower_bound ? s x ∧ (∀y:O.y ≰ x → ∃n.y ≰ s n).
definition increasing ≝ λO:ordered_set.λa:sequence O.∀n:nat.a n ≤ a (S n).
+definition decreasing ≝ λO:ordered_set.λa:sequence O.∀n:nat.a (S n) ≤ a n.
notation < "x \nbsp 'is_upper_bound' \nbsp s" non associative with precedence 50
for @{'upper_bound $s $x}.
-notation < "s \nbsp 'is_increasing'" non associative with precedence 50
+notation < "x \nbsp 'is_lower_bound' \nbsp s" non associative with precedence 50
+ for @{'lower_bound $s $x}.
+notation < "s \nbsp 'is_increasing'" non associative with precedence 50
for @{'increasing $s}.
-notation < "x \nbsp 'is_supremum' \nbsp s" non associative with precedence 50
+notation < "s \nbsp 'is_decreasing'" non associative with precedence 50
+ for @{'decreasing $s}.
+notation < "x \nbsp 'is_supremum' \nbsp s" non associative with precedence 50
for @{'supremum $s $x}.
+notation < "x \nbsp 'is_infimum' \nbsp s" non associative with precedence 50
+ for @{'infimum $s $x}.
notation > "x 'is_upper_bound' s" non associative with precedence 50
for @{'upper_bound $s $x}.
+notation > "x 'is_lower_bound' s" non associative with precedence 50
+ for @{'lower_bound $s $x}.
notation > "s 'is_increasing'" non associative with precedence 50
for @{'increasing $s}.
+notation > "s 'is_decreasing'" non associative with precedence 50
+ for @{'decreasing $s}.
notation > "x 'is_supremum' s" non associative with precedence 50
for @{'supremum $s $x}.
+notation > "x 'is_infimum' s" non associative with precedence 50
+ for @{'infimum $s $x}.
interpretation "Ordered set upper bound" 'upper_bound s x =
(cic:/matita/dama/supremum/upper_bound.con _ s x).
+interpretation "Ordered set lower bound" 'lower_bound s x =
+ (cic:/matita/dama/supremum/lower_bound.con _ s x).
interpretation "Ordered set increasing" 'increasing s =
(cic:/matita/dama/supremum/increasing.con _ s).
+interpretation "Ordered set decreasing" 'decreasing s =
+ (cic:/matita/dama/supremum/decreasing.con _ s).
interpretation "Ordered set strong sup" 'supremum s x =
(cic:/matita/dama/supremum/supremum.con _ s x).
+interpretation "Ordered set strong inf" 'infimum s x =
+ (cic:/matita/dama/supremum/infimum.con _ s x).
include "bishop_set.ma".
(* Lemma 2.6 *)
definition strictly_increasing ≝
λC:ordered_set.λa:sequence C.∀n:nat.a (S n) ≰ a n.
+definition strictly_decreasing ≝
+ λC:ordered_set.λa:sequence C.∀n:nat.a n ≰ a (S n).
+
notation < "s \nbsp 'is_strictly_increasing'" non associative with precedence 50
for @{'strictly_increasing $s}.
notation > "s 'is_strictly_increasing'" non associative with precedence 50
for @{'strictly_increasing $s}.
-interpretation "Ordered set increasing" 'strictly_increasing s =
+interpretation "Ordered set strict increasing" 'strictly_increasing s =
(cic:/matita/dama/supremum/strictly_increasing.con _ s).
+notation < "s \nbsp 'is_strictly_decreasing'" non associative with precedence 50
+ for @{'strictly_decreasing $s}.
+notation > "s 'is_strictly_decreasing'" non associative with precedence 50
+ for @{'strictly_decreasing $s}.
+interpretation "Ordered set strict decreasing" 'strictly_decreasing s =
+ (cic:/matita/dama/supremum/strictly_decreasing.con _ s).
notation "a \uparrow u" non associative with precedence 50 for @{'sup_inc $a $u}.
interpretation "Ordered set supremum of increasing" 'sup_inc s u =
(cic:/matita/dama/cprop_connectives/And.ind#xpointer(1/1)
(cic:/matita/dama/supremum/increasing.con _ s)
(cic:/matita/dama/supremum/supremum.con _ s u)).
+notation "a \downarrow u" non associative with precedence 50 for @{'inf_dec $a $u}.
+interpretation "Ordered set supremum of increasing" 'inf_dec s u =
+ (cic:/matita/dama/cprop_connectives/And.ind#xpointer(1/1)
+ (cic:/matita/dama/supremum/decreasing.con _ s)
+ (cic:/matita/dama/supremum/infimum.con _ s u)).
+include "nat/plus.ma".
include "nat_ordered_set.ma".
alias symbol "nleq" = "Ordered set excess".
cases (trans_increasing C ? Ia ?? H1); assumption;]
qed.
+(* Definition 2.7 *)
+alias symbol "exists" = "CProp exists".
+alias symbol "and" = "constructive and".
+definition order_converge ≝
+ λO:ordered_set.λa:sequence O.λx:O.
+ ∃l:sequence O.∃u:sequence O.
+ l is_increasing ∧ u is_decreasing ∧ l ↑ x ∧ u ↓ x ∧
+ ∀i:nat. (l i) is_infimum (λw.a (w+i)) ∧ (u i) is_supremum (λw.a (w+i)).
+
+notation < "a \nbsp (\circ \atop (\horbar\triangleright)) \nbsp x" non associative with precedence 50
+ for @{'order_converge $a $x}.
+notation > "a 'order_converges' x" non associative with precedence 50
+ for @{'order_converge $a $x}.
+interpretation "Order convergence" 'order_converge s u =
+ (cic:/matita/dama/supremum/order_converge.con _ s u).
+
+(* Definition 2.8 *)
+
+definition segment ≝ λO:ordered_set.λa,b:O.λx:O.
+ (cic:/matita/logic/connectives/And.ind#xpointer(1/1) (x ≤ b) (a ≤ x)).
+
+notation "[a,b]" non associative with precedence 50
+ for @{'segment $a $b}.
+interpretation "Ordered set sergment" 'segment a b =
+ (cic:/matita/dama/supremum/segment.con _ a b).
+
+notation "x \in [a,b]" non associative with precedence 50
+ for @{'segment2 $a $b $x}.
+interpretation "Ordered set sergment in" 'segment2 a b x=
+ (cic:/matita/dama/supremum/segment.con _ a b x).
+
+coinductive sigma (A:Type) (P:A→Prop) : Type ≝ sig_in : ∀x.P x → sigma A P.
+
+definition pi1 : ∀A.∀P.sigma A P → A ≝ λA,P,s.match s with [sig_in x _ ⇒ x].
+
+notation < "\pi \sub 1 x" non associative with precedence 50 for @{'pi1 $x}.
+notation < "\pi \sub 2 x" non associative with precedence 50 for @{'pi2 $x}.
+notation > "'fst' x" non associative with precedence 50 for @{'pi1 $x}.
+notation > "'snd' x" non associative with precedence 50 for @{'pi2 $x}.
+interpretation "sigma pi1" 'pi1 x =
+ (cic:/matita/dama/supremum/pi1.con _ _ x).
+
+interpretation "Type exists" 'exists \eta.x =
+ (cic:/matita/dama/supremum/sigma.ind#xpointer(1/1) _ x).
+
+lemma segment_ordered_set:
+ ∀O:ordered_set.∀u,v:O.ordered_set.
+intros (O u v); apply (mk_ordered_set (∃x.x ∈ [u,v]));
+[1: intros (x y); apply (fst x ≰ fst y);
+|2: intro x; cases x; simplify; apply os_coreflexive;
+|3: intros 3 (x y z); cases x; cases y ; cases z; simplify; apply os_cotransitive]
+qed.
+
+notation < "{\x|\x \in [a,b]}" non associative with precedence 90
+ for @{'segment_set $a $b}.
+interpretation "Ordered set segment" 'segment_set a b =
+ (cic:/matita/dama/supremum/segment_ordered_set.con _ a b).
+
+(* Lemma 2.9 *)
+lemma segment_preserves_supremum:
+ ∀O:ordered_set.∀l,u:O.∀a:sequence (segment_ordered_set ? l u).
+ ∀x:(segment_ordered_set ? l u).
+ (λn.fst (a n)) is_increasing ∧
+ (fst x) is_supremum (λn.fst (a n)) → a ↑ x.
+intros; split; cases H; clear H;
+[1: apply H1;
+|2: cases H2; split; clear H2;
+ [1: apply H;
+ |2: clear H; intro y0; apply (H3 (fst y0));]]
+qed.
+
+(* Definition 2.10 *)
+coinductive pair (A,B:Type) : Type ≝ prod : ∀a:A.∀b:B.pair A B.
+definition first : ∀A.∀P.pair A P → A ≝ λA,P,s.match s with [prod x _ ⇒ x].
+definition second : ∀A.∀P.pair A P → P ≝ λA,P,s.match s with [prod _ y ⇒ y].
+
+interpretation "pair pi1" 'pi1 x =
+ (cic:/matita/dama/supremum/first.con _ _ x).
+interpretation "pair pi2" 'pi2 x =
+ (cic:/matita/dama/supremum/second.con _ _ x).
+
+lemma square_ordered_set: ordered_set → ordered_set.
+intro O; apply (mk_ordered_set (pair O O));
+[1: intros (x y); apply (fst x ≰ fst y ∨ snd x ≰ snd y);
+|2: intro x0; cases x0 (x y); clear x0; simplify; intro H;
+ cases H (X X); apply (os_coreflexive ?? X);
+|3: intros 3 (x0 y0 z0); cases x0 (x1 x2); cases y0 (y1 y2) ; cases z0 (z1 z2);
+ clear x0 y0 z0; simplify; intro H; cases H (H1 H1); clear H;
+ [1: cases (os_cotransitive ??? z1 H1); [left; left|right;left]assumption;
+ |2: cases (os_cotransitive ??? z2 H1); [left;right|right;right]assumption]]
+qed.
+
+definition square_segment ≝
+ λO:ordered_set.λa,b:O.λx:square_ordered_set O.
+ (cic:/matita/logic/connectives/And.ind#xpointer(1/1)
+ (cic:/matita/logic/connectives/And.ind#xpointer(1/1) (fst x ≤ b) (a ≤ fst x))
+ (cic:/matita/logic/connectives/And.ind#xpointer(1/1) (snd x ≤ b) (a ≤ snd x))).
+
+definition convex ≝
+ λO:ordered_set.λU:square_ordered_set O → Prop.
+ ∀p.U p → fst p ≤ snd p → ∀y. square_segment ? (fst p) (snd p) y → U y.
+
+(* Definition 2.11 *)
+definition upper_located ≝
+ λO:ordered_set.λa:sequence O.∀x,y:O. y ≰ x →
+ (∃i:nat.a i ≰ x) ∨ (∃b:O.y≰b ∧ ∀i:nat.a i ≤ b).
+
+(* Lemma 2.12 *)
+lemma uparrow_located:
+ ∀C:ordered_set.∀a:sequence C.∀u:C.a ↑ u → upper_located ? a.
+intros (C a u H); cases H (H2 H3); clear H; intros 3 (x y Hxy);
+cases H3 (H4 H5); clear H3; cases (os_cotransitive ??? u Hxy) (W W);
+[2: cases (H5 ? W) (w Hw); left; exists [apply w] assumption;
+|1: right; exists [apply u]; split; [apply W|apply H4]]
+qed.
+
+
+
\ No newline at end of file
projects / helm.git / commitdiff