Commit 7c649129 authored by François Bobot's avatar François Bobot

[Theory] add sum of a container following a finite set

parent 2fcac2a3
......@@ -291,6 +291,49 @@ theory Min
end
(** sum on finite set *)
theory FsetSum "Sum of the elements of a container limited to a finite set of keys"
use import int.Int
use import Fset as S
type key
type container
function f container key : int
(** [f c k] is the element associated to k in the container [c] *)
function sum container (set key) : int
(** [sum c s] is the sum Sum_{S.mem k s} f c k *)
axiom Sum_def_empty :
forall c : container. sum c S.empty = 0
axiom Sum_add:
forall c : container, s : set key, k: key.
not (mem k s) -> sum c (S.add k s) = sum c s + f c k
lemma Sum_remove:
forall c : container, s : set key, k: key.
mem k s -> sum c (S.remove k s) = sum c s - f c k
lemma Sum_def_choose :
forall c: container, s:set key.
not (S.is_empty s) ->
let k = S.choose s in
sum c s = f c k + sum c (S.remove k s)
lemma Sum_transitivity :
forall c : container, s1 s2 : set key.
sum c (S.union s1 s2) = sum c s1 + sum c s2 - sum c (S.inter s1 s2)
lemma Sum_eq :
forall c1 c2 : container, s : set key.
(forall k : key. S.mem k s -> f c1 k = f c2 k) -> sum c1 s = sum c2 s
end
(** {2 Sets realized as maps} *)
theory SetMap
......
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