Tyler Jarvis (BYU)
12 - 2 - 98


"Compactification of the Universal Picard
over the Moduli of Stable Curves"


ABSTRACT:  I will discuss the construction of a stack, which in
characteristic zero provide a type of compactification of the
universal Picard over the moduli of stable curves.  Although not  of
finite type, it is the limit of a sequence of stacks, each of which is
a separated algebraic stack of finite type.  I will discuss relations
to previous compactifications and partial compactifications, give a
number of examples related to this compactification, and work out the
structure of its fibres over certain fixed curves.  Some applications
will also be discussed.