Changes

# Algebra+topology: discussion of fundamental group.

# Algebra+topology: discussion of fundamental group.

# Analysis+topology: discuss conservative fields, and hint at de Rham cohomology without actually saying those words.

# Analysis+topology: discuss conservative fields, and hint at de Rham cohomology without actually saying those words.

# Algebra+analysis: find a good simple example of a Lie group showing up in the study of some differential equations.

# Algebra+analysis: The set of derivations on the tangent bundle of a smooth manifold form a Lie algebra, connecting solutions to partial differential equations and algebra.

== So What? ==

== So What? ==