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
+notation "hvbox(x \in break [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).
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' \nbsp x" non associative with precedence 50 for @{'pi1 $x}.
+notation < "'snd' \nbsp 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).
|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
+notation "hvbox({[a, break 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).
+ ∀O:ordered_set.∀l,u:O.∀a:sequence {[l,u]}.∀x:{[l,u]}.
(λn.fst (a n)) is_increasing ∧
(fst x) is_supremum (λn.fst (a n)) → a ↑ x.
intros; split; cases H; clear H;
(cic:/matita/dama/supremum/first.con _ _ x).
interpretation "pair pi2" 'pi2 x =
(cic:/matita/dama/supremum/second.con _ _ x).
+
+notation "hvbox(\langle a, break b\rangle)" non associative with precedence 91 for @{ 'pair $a $b}.
+interpretation "pair" 'pair a b =
+ (cic:/matita/dama/supremum/pair.ind#xpointer(1/1/1) _ _ a b).
+
+notation "a \times b" left associative with precedence 60 for @{'prod $a $b}.
+interpretation "prod" 'prod a b =
+ (cic:/matita/dama/supremum/pair.ind#xpointer(1/1) a b).
lemma square_ordered_set: ordered_set → ordered_set.
-intro O; apply (mk_ordered_set (pair O O));
+intro O; apply (mk_ordered_set (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);
[1: cases (os_cotransitive ??? z1 H1); [left; left|right;left]assumption;
|2: cases (os_cotransitive ??? z2 H1); [left;right|right;right]assumption]]
qed.
+
+notation < "s 2 \atop \nleq" non associative with precedence 90
+ for @{ 'square $s }.
+notation > "s 'square'" non associative with precedence 90
+ for @{ 'square $s }.
+interpretation "ordered set square" 'square s =
+ (cic:/matita/dama/supremum/square_ordered_set.con s).
definition square_segment ≝
λO:ordered_set.λa,b:O.λx:square_ordered_set O.
(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.
+ λO:ordered_set.λU:O square → Prop.
∀p.U p → fst p ≤ snd p → ∀y. square_segment ? (fst p) (snd p) y → U y.
(* Definition 2.11 *)