A survey of Magnus representations for mapping class groups and homology cobordisms of surfaces
arXiv:1005.5501
Abstract
This is a survey of Magnus representations with particular emphasis on their applications to mapping class groups and monoids (groups) of homology cobordisms of surfaces. In the first half, we begin by recalling the basics of the Fox calculus and overview Magnus representations for automorphism groups of free groups and mapping class groups of surfaces with related topics. In the latter half, we discuss in detail how the theory in the first half extends to homology cobordisms of surfaces and present a number of applications from recent researches.
69 pages. The statement of Proposition 6.1 is corrected. Submitted to "Handbook of Teichmu"ller theory, volume III" (editor: A. Papadopoulos)