“…The objective functions in Equations (11) and (12) have problems of singularity and nondifferentiability with respect to shape variation. Since the KS function, a power function of exponential has sufficiently differentiable smoothness, the authors have used it for various min‐max problems,
40,41 and confirmed its effectiveness. Besides the KS function, a function called l p ‐norm
can also be used for the same purpose.…”