Definition knot_rel (k1 k2:knot) :=
let (n,f) := unsquash k1 in
let (n',f') := unsquash k2 in
n = n' /\ KI.Rel predicate f f'.

Axiom knot_rel_spec: forall k1 k2: knot,
knot_rel k1 k2 = KO.K0.knot_rel k1 k2.