Rank gradient and p-gradient of amalgamated free products and HNN extensions
Mathematics - Group Theory | 20E06, 20E15, 20F69
arxiv: Mathematics::Group Theory | Mathematics::Operator Algebras
We calculate the rank gradient and p-gradient of free products, free products with amalgamation over an amenable subgroup, and HNN extensions with an amenable associated subgroup. The notion of cost is used to compute the rank gradient of amalgamated free products and HNN extensions. For the p-gradient the Kurosh subgroup theorems for amalgamated free products and HNN extensions will be used.