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15 set "baseuri" "cic:/matita/RELATIONAL/Zah/defs".
17 include "datatypes/constructors.ma".
18 include "logic/coimplication.ma".
19 include "NPlusList/defs.ma".
21 definition Zah \def Nat \times Nat.
23 definition ZEq: Zah \to Zah -> Prop :=
25 \forall n. ((\fst z1) + (\snd z2) == n) \liff (\fst z2) + (\snd z1) == n.
27 interpretation "integer equality" 'zeq x y =
28 (cic:/matita/RELATIONAL/Zah/defs/ZEq.con x y).
30 notation "hvbox(a break = b)"
31 non associative with precedence 45