Cubic complexes appear in the theory of finite type invariants so often that
one can ascribe them to basic notions of the theory. In this paper we begin the
exposition of finite type invariants from the `cubic' point of view. Finite
type invariants of knots and homology 3-spheres fit perfectly into this
conception. In particular, we get a natural explanation why they behave like
polynomials.Comment: Published by Geometry and Topology Monographs at
http://www.maths.warwick.ac.uk/gt/GTMon4/paper14.abs.htm