3 papers
math.CO2026
Small -kernels in digraphs
Irena Penev, Maya Stein, Ana Trujillo-Negrete
We address three questions of Spiro [Europ. J. Combin., 133:Paper No. 104307, 2026] on smallest -kernels in digraphs. All three questions are on the existence of small -kerne…
math.CO2025
Isometric and induced path partitions: a new upper bound and a characterization of some extremal graphs
Irena Penev, R. B. Sandeep, D. K. Supraja +1
An \textit{isometric path} is a shortest path between two vertices. An \textit{isometric path partition} (IPP) of a graph is a set of vertex-disjoint isometric pa…
math.CO2025
Two-block paths in oriented graphs of large semidegree
Irena Penev, S Taruni, Stéphan Thomassé +2
We study the existence of oriented paths with two blocks in oriented graphs under semidegree conditions. A block of an oriented path is a maximal directed subpath. Given positive i…