Let Ω denote the disc
x12 + x22 < r2 in the x = (x1,x2) plane from which the segment {0 ≦ x1 < r,x2 = 0}
has been deleted. Suppose that u(x) ∈ C0(Ω) is a solution to the minimal surface
equation in Ω ((1) below) and attains boundary values f(x1) ∈ C1,α(0 < α < 1)
on the slit {0 ≦ x1 < r,x2 = 0}. We shall prove here that the gradient of
u,Du = (ux1,ux2), is continuous at the origin x = 0.
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