Fermat limit and congruence of Ohtsuki invariants
arXiv:math/9810147
Abstract
By calculating the Fermat limit of certain q-Fermat functions, we get explicit surgery formulae for the second and third Ohtsuki invariants for homology 3-spheres. The surgery formula of the second Ohtsuki invariant λ_2, combined with an argument using the general theory of finite type invariants of homology 3-spheres, leads to a congruence relation between the first and second Ohtsuki invariants: λ_1=2λ_2 mod 24.
13 pages. Published copy, also available at http://www.maths.warwick.ac.uk/gt/GTMon2/paper17.abs.html