Title: Almost Congruence Extension Property for subgroups of free groups.

Abstract.

The talk essentially based on: https://arxiv.org/abs/1606.02345

Let G be a group and H every normal subgroup N of H is an intersection of some normal subgroup of G with H. The CEP appears in group theory in different context.

The following question seems to be very difficult:

Which finitely generated subgroup of a free group has CEP?

D. Osin considers the weaker property -- the almost congruence extension property (ACEP). In the talk I define and

discuss ACEP and almost answer the question:

Which finitely generated subgroup of a free group has ACEP?

Also I plan to present several examples of subgroups to illustrate results and open problems.

Abstract.

The talk essentially based on: https://arxiv.org/abs/1606.02345

Let G be a group and H every normal subgroup N of H is an intersection of some normal subgroup of G with H. The CEP appears in group theory in different context.

The following question seems to be very difficult:

Which finitely generated subgroup of a free group has CEP?

D. Osin considers the weaker property -- the almost congruence extension property (ACEP). In the talk I define and

discuss ACEP and almost answer the question:

Which finitely generated subgroup of a free group has ACEP?

Also I plan to present several examples of subgroups to illustrate results and open problems.

## Date:

Thu, 02/03/2017 - 12:00 to 13:00

## Location:

Manchester Building, Room 209