is the differential of the distance function holomorphic? - MathOverflow most recent 30 from http://mathoverflow.net 2013-05-23T20:11:02Z http://mathoverflow.net/feeds/question/72826 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/72826/is-the-differential-of-the-distance-function-holomorphic is the differential of the distance function holomorphic? miriam 2011-08-13T10:11:01Z 2011-08-13T23:15:43Z <p>i have the following problem. Let $M$ be a complex n-dim manifold and $X \subset M$ be a n-dim real analytic submanifold. Consider $d_{X}(z)$ be the squared distance from $z \in M$ to $X$. For $z$ sufficiently near $X$ this function is smooth. My quaestion is: Is (with respect to complex coordinates $z_{1}, ..., z_{n}$) the function $\partial^{2} d_{X} / \partial z_{i} \partial \bar z_{j}$ is holomorphic? (assume that we have alredy choosen a hermitian metric to compute $d_{X}$). </p> http://mathoverflow.net/questions/72826/is-the-differential-of-the-distance-function-holomorphic/72828#72828 Answer by Henri for is the differential of the distance function holomorphic? Henri 2011-08-13T10:30:10Z 2011-08-13T23:15:43Z <p>Take the most simple example $M=\mathbb C$ and $X$ the unit circle. Then $d_X(z)=|z-\frac{z}{|z|}|^2$ is not holomorphic (so as its Laplacian $i\partial \bar \partial( d_X)$), as you can easily see by expanding the expression.</p>