In this paper, we consider a Generalized Bernstein Theorem for a type of generalized minimal surfaces, namely minimal Plateau surfaces. We show that if a complete orientable minimal Plateau surface is stable and has quadratic area growth in $R^3$, then it is flat.
Main results
The classical Bernstein question is extended from smooth minimal surfaces to
Plateau surfaces, whose local models may also contain $Y$- and $T$-type soap-film
singularities.
Generalized Bernstein theorem
Stability and quadratic area growth force flatness
If a complete orientable minimal Plateau surface in $\mathbb R^3$ is stable and has at most quadratic area growth, then every component of its regular part lies in a plane.
No $T$-points
The surface is cylindrical over a planar network
When no $T$-type singularity occurs, the surface is, after a rigid motion, of the form $N\times\mathbb R$ for an embedded stationary network $N\subset\mathbb R^2$.
With $T$-points
Only two global configurations remain
If $T$-type singularities occur, there is either one such point and the surface is the standard $T$ cone, or there are exactly two points joined in the explicitly classified flat configuration.
Proof strategy
The proof transfers the stability inequality to the regular sheets while
retaining the balancing information along the singular curves. Curvature
estimates and logarithmic cutoffs, made possible by quadratic area growth,
force the second fundamental form to vanish. Once each sheet is planar, the
topology and Plateau angle conditions reduce the remaining work to a global
classification of the straight $Y$-curves and isolated $T$-points.