Seminár z teórie grafov - František Kardoš (12.11.2020)

vo štvrtok 12.11.2020o 9:50 hod.


10. 11. 2020 14.15 hod.
Od: Martin Škoviera

Prednášajúci: František Kardoš (FMFI UK, LABRI University of Bordeaux)

Názov: On the 4-color theorem for signed graphs

Termín: 12.11.2020, 9:50 hod.

Prístupový kód do MS TEAMS (pre používateľov z UK): gglxxc7 
Pripojenie (pre hostí mimo UK)


Abstrakt:
Macajova, Raspaud and Skoviera defined the chromatic number of a signed graph which coincides for all-positive signed graphs with the chromatic number of unsigned graphs. They conjectured that in this setting, for signed planar graphs four colors are always enough, thereby generalising The Four Color Theorem. We disprove the conjecture.

Stránka seminára