Montel's theorem and tautness in calibrated geometry

Abstract

We relate the hyperbolicity of a calibrated manifold $(X,\varphi )$ to the analytic properties of the space of Smith immersions $\mathrm{SmIm}(B^k,X)$ from the Poincare $k$-ball into $X$. In particular, we establish the following calibrated analogue of a theorem of Royden: if $X$ is $\varphi$-replete, then $R_{\varphi }$- and $K_{\varphi }$-hyperbolicity coincide, and either implies the equicontinuity of $\mathrm{SmIm}(B^k,X)$ with respect to the $\varphi$-distance. This yields a Montel theorem for compact $\varphi$-replete calibrated manifolds as an immediate corollary. Our primary technical tool is a new Schwarz lemma for Smith immersions from $B^k$ into $X$, which is of independent interest. In a similar spirit, we also prove a calibrated analogue of Kiernan's theorem to the effect that the $K_{\varphi }$-hyperbolicity of $X$ is almost equivalent to $\mathrm{SmIm}(B^k,X)$ being a normal family. Finally, we prove that bounded domains in flat euclidean space are $R_{\varphi }$-hyperbolic for any calibration $\varphi$, and we investigate the hyperbolicity of products and discrete quotients.

27 pages. Version 2: Minor corrections and restructuring