qualif Nat(v:int) : (0 <= v) bind 0 x : {v: int | [$k0]} bind 1 y : {v: int | [$k0]} bind 2 z : {v: int | [$k1]} constraint: env [ ] lhs {v : int | [v = 10]} rhs {v : int | [$k0]} id 1 tag [0] constraint: env [ 0 ] lhs {v : int | [v = x + x]} rhs {v : int | [$k0]} id 2 tag [0] constraint: env [ 0; 1 ] lhs {v : int | [v = x + y ]} rhs {v : int | [$k1]} id 3 tag [0] constraint: env [ 2 ] lhs {v : int | [v = z]} rhs {v : int | [0 <= v]} id 4 tag [0] wf: env [ ] reft {v: int | [$k0]} wf: env [ ] reft {v: int | [$k1]}