COOKIES: By using this website you agree that we can place Google Analytics Cookies on your device for performance monitoring. |

University of Cambridge > Talks.cam > Isaac Newton Institute Seminar Series > Uncountably many maximal-closed subgroups of Sym(N) via reducts of Henson digraphs

## Uncountably many maximal-closed subgroups of Sym(N) via reducts of Henson digraphsAdd to your list(s) Download to your calendar using vCal - Agarwal, L (University of Leeds)
- Friday 09 October 2015, 15:50-16:45
- Seminar Room 2, Newton Institute Gatehouse.
If you have a question about this talk, please contact webseminars. Mathematical, Foundational and Computational Aspects of the Higher Infinite This work contributes to the two closely related areas of countable homogeneous structures and infinite permutation groups. In the permutation group side, we answered a question of Macpherson that asked to show that there are uncountably many pairwise non-conjugate maximal-closed subgroups of Sym(mathbb{N}). This was achieved by taking the automorphism groups of uncountably many pairwise non-isomorphic Henson digraphs. The fact these groups are maximal-closed follows from the classification of the reducts of Henson digraphs. In itself, this classification contributes to the building list of structures whose reducts are known and also provides further evidence that Thomas’ conjecture is true. In this talk, my main aim will be to describe the construction of these continuum many maximal-closed subgroups, which will include Henson’s famous construction of continuum many countable homogeneous digraphs. Any remaining time will be spent giving some of the ideas behind how we prove these groups are maximal closed. This talk is part of the Isaac Newton Institute Seminar Series series. ## This talk is included in these lists:- All CMS events
- Featured lists
- INI info aggregator
- Isaac Newton Institute Seminar Series
- School of Physical Sciences
- Seminar Room 2, Newton Institute Gatehouse
- bld31
Note that ex-directory lists are not shown. |
## Other listsBabbage Lecture Series Wolfson Press Fellowship Microsoft Research Machine Learning and Perception Seminars Statistics Type the title of a new list here Effective Altruism: Cambridge## Other talksPrivate Statistics and Their Applications to Distributed Learning: Tools and Challenges Inelastic neutron scattering and µSR investigations of an anisotropic hybridization gap in the Kondo insulators: CeT2Al10 (T=Fe, Ru and Os) Strong Bonds, Affective Labour: Sexually Transmitted Infections and the Work of History Disease Migration Cycles of Revolution in Ukraine Using vision to understand dementia in Parkinson’s disease |