Speaker
Michał Krysiak
Description
The Nielsen–Schreier theorem states that a subgroup of a free group is itself a free group, giving also a formula for the number of generators of the subgroup when its index is known and finite. While the first statement sounds somewhat obvious, it is not completely straightforward to show. Moreover, the second part shows that subgroups of free groups can have arbitrarily many generators. In this talk I wish to present a non-advanced and, hopefully, intuitive proof of the above theorem.
| Field | Mathematics |
|---|---|
| Length | Long 20 min |
Author
Michał Krysiak
