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# Mark Siggers, The list switch homomorphism problem for signed graphs

## Tuesday, May 11, 2021 @ 4:30 PM - 5:30 PM KST

Room B232, IBS (기초과학연구원)

### Speaker

Mark Siggers
Kyungpook National University
http://webbuild.knu.ac.kr/~mhs/

A signed graph is a graph in which each edge has a positive or negative sign. Calling two graphs switch equivalent if one can get from one to the other by the iteration of the local action of switching all signs on edges incident to a given vertex, we say that there is a switch homomorphism from a signed graph $G$ to a signed graph $H$ if there is a sign preserving homomorphism from $G’$ to $H$ for some graph $G’$ that is switch equivalent to $G$.  By reductions to CSP this problem, and its list version, are known to be either polynomial time solvable or NP-complete, depending on $H$.  Recently those signed graphs $H$ for which the switch homomorphism problem is in $P$ were characterised.  Such a characterisation is yet unknown for the list version of the problem.

We talk about recent work towards such a characterisation and about how these problems fit in with bigger questions that still remain around the recent CSP dichotomy theorem.

## Details

Date:
Tuesday, May 11, 2021
Time:
4:30 PM - 5:30 PM KST
Event Category:
Event Tags:

Room B232
IBS (기초과학연구원)

## Organizer

Sang-il Oum (엄상일)
View Organizer Website
기초과학연구원 수리및계산과학연구단 이산수학그룹
대전 유성구 엑스포로 55 (우) 34126
IBS Discrete Mathematics Group (DIMAG)
Institute for Basic Science (IBS)
55 Expo-ro Yuseong-gu Daejeon 34126 South Korea
E-mail: dimag@ibs.re.kr, Fax: +82-42-878-9209