Now showing items 1-1 of 1
HNN- EXTENSIONS OF FINITE INVERSE SEMIGROUPS
(POLITECNICO DI M ILANO D EPARTMENT OF M ATHEMATICS, 2014)
The concept of HNN-extensions of groups was introduced by Higman, Neumann and Neumann in 1949. HNN-extensions and amalgamated free products have played a crucial role in combinatorial group theory, especially for algorithmic ...