  There is a close analogy between the response of a quantum Hall liquid (QHL)
to a small change in the electron density and the response of a superconductor
to an externally applied magnetic flux - an analogy which is made concrete in
the Chern-Simons Landau-Ginzburg (CSLG) formulation of the problem. As the
Types of superconductor are distinguished by this response, so too for QHLs: a
typology can be introduced which is, however, richer than that in
superconductors owing to the lack of any time-reversal symmetry relating
positive and negative fluxes. At the boundary between Type I and Type II
behavior, the CSLG action has a "Bogomol'nyi point," where the quasi-holes
(vortices) are non-interacting - at the microscopic level, this corresponds to
the behavior of systems governed by a set of model Hamiltonians which have been
constructed to render exact a large class of QHL wavefunctions. All Types of
QHLs are capable of giving rise to quantized Hall plateaux.
