 One way to interpret this is that these variables formula_5 and its dual can be expressed as periods of a meromorphic differential on a Riemann surface called the Seiberg–Witten curve.The special Kähler geometry on the moduli space of vacua in Seiberg–Witten theory can be identified with the geometry of the base of complex completely integrable system.The total phase of this complex completely integrable system can be identified with the moduli space of vacua of the 4d theory compactified on a circle.