Abstract
We give various estimates of the minimal number of self-intersections of a nontrivial element of the kth term of the lower central series and derived series of the fundamental group of a surface. As an application, we obtain a new topological proof of the fact that free groups and fundamental groups of closed surfaces are residually nilpotent. Along the way, we prove that a nontrivial element of the kth term of the lower central series of a nonabelian free group has to have word length at least k in a free generating set.
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Ahlfors L.V., Sario L.: Riemann Surfaces. Princeton University Press, Princeton, NJ (1960)
Baumslag G.: On generalised free products. Math. Z. 78, 423–438 (1962)
Chen K.-T., Fox R.H., Lyndon R.C.: Free differential calculus. IV. The quotient groups of the lower central series. Ann. Math. 68(2), 81–95 (1958)
Fox R.H.: Free differential calculus. I. Derivation in the free group ring. Ann. Math. 57(2), 547–560 (1953)
Frederick K.N.: The Hopfian property for a class of fundamental groups. Comm. Pure Appl. Math. 16, 1–8 (1963)
Hempel J.: Residual finiteness of surface groups. Proc. Am. Math. Soc. 32, 323 (1972)
Magnus W.: Beziehungen zwischen Gruppen und Idealen in einem speziellen ring. Math. Ann. 111(1), 259–280 (1935)
Massey W.S.: Algebraic Topology: An Introduction. Harcourt, Brace & World, Inc., New York (1967)
Reznikov, A.: Crossing number and lower central series of a surface group. Unpublished preprint (1998)
Rotman J.J.: An Introduction to the Theory of Groups, 4th edn. Springer, New York (1995)
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Malestein, J., Putman, A. On the self-intersections of curves deep in the lower central series of a surface group. Geom Dedicata 149, 73–84 (2010). https://doi.org/10.1007/s10711-010-9465-z
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DOI: https://doi.org/10.1007/s10711-010-9465-z