Definition table (A B : Type) := list (A*B).
Fixpoint table_get {A B}{H: EqDec A} (rho: table A B) (x: A) : option B :=
match rho with
| (y,v)::ys => if eq_dec x y then Some v else table_get ys x
| nil => None
end.
Definition table_set {A B}{H: EqDec A} (x: A) (v: B) (rho: table A B)  : table A B := (x,v)::rho.

Lemma table_gso {A B}{H: EqDec A}: forall rho x y (v:B), x<>y -> table_get (table_set x v rho) y = table_get rho y.