Published online by Cambridge University Press: 20 November 2018
A line singularity is a function germ $f:\,\left( {{\text{C}}^{n+1}},\,0 \right)\,\to \,\text{C}$ with a smooth 1-dimensional critical set $\sum \,=\,\left\{ \left( x,\,y \right)\,\in \,\text{C}\,\times \,{{\text{C}}^{n}}\,|\,y\,=\,0 \right\}$. An isolated line singularity is defined by the condition that for every $x\,\ne \,0$, the germ of $f$ at $\left( x,\,0 \right)$ is equivalent to $y_{1}^{2}\,+\,\cdot \,\cdot \,\cdot \,+\,y_{n}^{2}$. Simple isolated line singularities were classified by Dirk Siersma and are analogous of the famous $A\,-\,D\,-E$ singularities. We give two new characterizations of simple isolated line singularities.