Molecular Cloud Fragmentation and Core Collapse
  I review some steps in the conversion of molecular cloud gas into stars and
planets, with an emphasis in this presentation on the early stage molecular
cloud fragmentation that leads to elongated filaments/ribbons. Magnetic fields
can play a crucial role in all stages and need to be invoked particularly for
early stage fragmentation as well as in late core collapse where it may control
disk formation. I also review some elements of hydrodynamic modeling of disk
evolution.
