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Big mod [l] monodromy for families of [G] covers

Jain, Lalit Kumar, dissertant

Publication Details Click to collapse Cite/Export

  • Creator by Lalit Jain
  • Format Books
  • Publication [Madison, Wis.] : [University of Wisconsin--Madison], 2016.
  • Physical Details
    • 1 online resource (vi, 63 pages) : illustrations
  • OCLC ocn956736166


  • The monodromy of a family of varieties is a measure of how homology classes vary. Surprisingly, many familiar ideas in number theory, such as Galois representations and Cohen-Lenstra heuristics, are closely linked to the monodromy of specific families. In general, we expect the monodromy of a family to be ``big'', i.e. as large as possible subject to any geometrical or algebraic constraints arising from the family. In this thesis I study the monodromy of Hurwitz spaces of [G]-covers, moduli spaces for branched covers of the projective line with Galois group [G]. I show that if [G] is center-free and has trivial Schur multiplier the mod [l] monodromy will be big as long as the number of branch points of a curve in the family is chosen to be sufficiently large. Along the way the necessary algebraic results, including a generalized equivariant Witt's lemma, are presented. The proof relies on a characterization of the connected components of Hurwitz Spaces due to Ellenberg, Venkatesh, and Westerland that generalizes an older result of Conway-Parker and Fried Völklein. Connections to current results on monodromy of cyclic covers are also discussed.


  • On title page [l] is represented by a script "l".
  • On title page [G] is italicized.
  • Adviser: Jordan S. Ellenberg.
  • Ph.D. University of Wisconsin--Madison 2016.
  • Includes bibliographical references (pages 59-63).