x1=fan1=fr1 is a bijective function / isomorphism from x2=fan2 to x3=fan3, with inverse x4, in system / category x5; x1 has an inverse; x1 is a function that is injective and surjective; x2 and x3 are isomorphic; x1 is invertible.
x1 is passively x2-able (especially «se x2») under conditions x3; x1 is such that event x2 (nu) can happen to it; it is possible that x1 may undergo x2.
x1=z1=t2 (e.g. abstraction, energy) is potential / potentially real, made real when / under conditions x2=t1 for x3=z2 under metaphysics / conceptual framework / model x4=z3.