const {:existential true} b1:bool; const {:existential true} b2:bool; const {:existential true} b3:bool; const {:existential true} b4:bool; const {:existential true} b5:bool; const {:existential true} b6:bool; const {:existential true} b7:bool; const {:existential true} b8:bool; var array:[int]int; procedure foo (i:int) requires b6 ==> i < 0; requires b5 ==> i == 0; requires b2 ==> i > 0; ensures b3 ==> array[i] > 0; modifies array; ensures (forall x:int :: {array[x]} x == i || array[x] == old(array)[x]); { array[i] := 2 * i; } procedure bar (j:int) returns (result:int) requires b8 ==> j < 0; requires b7 ==> j == 0; requires b4 ==> j > 0; modifies array; ensures (forall x:int :: {array[x]} (x == j) || array[x] == old(array)[x]); ensures (b1 ==> array[j] == old(array)[j]); { call foo(j); result := array[j]; } var p:int; procedure main() returns (result: int) modifies array; { call result:= bar(p); } // expected outcome: Correct // expected assigment: bi->True forall i