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math.CO2019
Flows on signed graphs without long barbells
You Lu, Rong Luo, Michael Schubert +2
Many basic properties in Tutte's flow theory for unsigned graphs do not have their counterparts for signed graphs. However, signed graphs without long barbells in many ways behave…
math.CO2017
Plane graphs without 4- and 5-cycles and without ext-triangular 7-cycles are 3-colorable
Ligang Jin, Yingli Kang, Michael Schubert +1
Listed as No. 53 among the one hundred famous unsolved problems in [J. A. Bondy, U. S. R. Murty, Graph Theory, Springer, Berlin, 2008] is Steinberg's conjecture, which states that…
math.CO2016
Signed graphs with two negative edges
Edita Rollová, Michael Schubert, Eckhard Steffen
The presented paper studies the flow number of flow-admissible signed graphs with two negative edges. We restrict our study to cubic graphs, because for each non-c…