+[apply (mpositive ? (ml_mspace_ ? ml));|apply (mreflexive ? (ml_mspace_ ? ml));
+|apply (msymmetric ? (ml_mspace_ ? ml));|apply (mtineq ? (ml_mspace_ ? ml))]
+qed.
+
+coercion cic:/matita/metric_lattice/ml_mspace.con.
+
+alias symbol "plus" = "Abelian group plus".
+record mlattice (R : todgroup) : Type ≝ {
+ ml_carr :> mlattice_ R;
+ ml_prop1: ∀a,b:ml_carr. 0 < δ a b → a # b;
+ ml_prop2: ∀a,b,c:ml_carr. δ (a∨b) (a∨c) + δ (a∧b) (a∧c) ≤ δ b c
+}.
+
+lemma eq_to_ndlt0: ∀R.∀ml:mlattice R.∀a,b:ml. a ≈ b → ¬ 0 < δ a b.
+intros (R ml a b E); intro H; apply E; apply ml_prop1;
+assumption;
+qed.
+
+lemma eq_to_dzero: ∀R.∀ml:mlattice R.∀x,y:ml.x ≈ y → δ x y ≈ 0.
+intros (R ml x y H); intro H1; apply H; clear H;
+apply ml_prop1; split [apply mpositive] apply ap_symmetric;
+assumption;
+qed.
+
+lemma meq_l: ∀R.∀ml:mlattice R.∀x,y,z:ml. x≈z → δx y ≈ δz y.
+intros (R ml x y z); apply le_le_eq;
+[ apply (le_transitive ???? (mtineq ???y z));
+ apply (le_rewl ??? (0+δz y) (eq_to_dzero ???? H));
+ apply (le_rewl ??? (δz y) (zero_neutral ??)); apply le_reflexive;
+| apply (le_transitive ???? (mtineq ???y x));
+ apply (le_rewl ??? (0+δx y) (eq_to_dzero ??z x H));
+ apply (le_rewl ??? (δx y) (zero_neutral ??)); apply le_reflexive;]
+qed.
+
+(* 3.3 *)
+lemma meq_r: ∀R.∀ml:mlattice R.∀x,y,z:ml. x≈z → δy x ≈ δy z.
+intros; apply (eq_trans ???? (msymmetric ??y x));
+apply (eq_trans ????? (msymmetric ??z y)); apply meq_l; assumption;
+qed.
+
+
+lemma dap_to_lt: ∀R.∀ml:mlattice R.∀x,y:ml. δ x y # 0 → 0 < δ x y.
+intros; split [apply mpositive] apply ap_symmetric; assumption;
+qed.
+
+lemma dap_to_ap: ∀R.∀ml:mlattice R.∀x,y:ml. δ x y # 0 → x # y.
+intros (R ml x y H); apply ml_prop1; split; [apply mpositive;]
+apply ap_symmetric; assumption;
+qed.
+
+interpretation "Lattive meet le" 'leq a b =
+ (cic:/matita/excess/le.con (cic:/matita/lattice/excess_OF_lattice1.con _) a b).
+
+interpretation "Lattive join le (aka ge)" 'geq a b =
+ (cic:/matita/excess/le.con (cic:/matita/lattice/excess_OF_lattice.con _) a b).
+
+lemma le_to_ge: ∀l:lattice.∀a,b:l.a ≤ b → b ≥ a.
+intros(l a b H); apply H;