Transverse slices and Zariski's multiplicity conjecture for quasihomogeneous surfaces

Abstract: In this work, we study finitely determined, quasihomogeneous, corank 1 map germs $f$ from $(\mathbb{C}^2,0)$ to $(\mathbb{C}^3,0)$. We introduce the notion of the $\mu_{\boldsymbol{m},\boldsymbol{k}}$-minimal transverse slice of $f.$ Since this slice is a plane curve, we provide its (topological) normal form. In the irreducible case, under certain conditions, we prove that the number of characteristic exponents of the curve is upper semicontinuous. Furthermore, we show that every topologically trivial 1-parameter unfolding of $f=(f_1,f_2,f_3)$ (not necessarily with $\mu_{\boldsymbol{m},\boldsymbol{k}}$-minimal transverse slice) is of non-negative degree (i.e., for any additional term $\alpha$ in the deformation of $f_i$, the weighted degree of $\alpha$ is not smaller than the weighted degree of $f_i$). As a consequence, we present a proof of Zariski\' s multiplicity conjecture for families in this setting. Finally, under the $\mu_{\boldsymbol{m},\boldsymbol{k}}$-minimal transverse slice assumption, we show that Ruas\' conjecture holds.