  The augmentation variety of a knot is the locus, in the 3-dimensional
coefficient space of the knot contact homology dg-algebra, where the algebra
admits a unital chain map to the complex numbers. We explain how to express the
Alexander polynomial of a knot in terms of the augmentation variety: it is the
exponential of the integral of a ratio of two partial derivatives. The
expression is derived from a description of the Alexander polynomial as a count
of Floer strips and holomorphic annuli, in the cotangent bundle of Euclidean
3-space, stretching between a Lagrangian with the topology of the knot
complement and the zero-section, and from a description of the boundary of the
moduli space of such annuli with one positive puncture.
