Susumu Hirose

Lefschetz fibrations with handlebody monodromy

We study relatively minimal Lefschetz fibrations over closed oriented surfaces whose monodromy extends over a fixed 3--dimensional handlebody. If $X$ is the total space and $\ell$ is the number of critical points, we prove that $\sigma(X)=-\ell$. Such fibrations with $\ell>0$ exist precisely for fiber genus $g\geq3$ an...