On the Existence and the Number of \((2-d)\)-Kernels in Graphs

Pawel Bednarz1, Iwona Wloch1, César Hernandez-Cruz2
1Faculty of Mathematics and Applied Physic Rzeszow University ff Technology al. Powstaricéw Warszawy 8 35-959 Rzeszow, Poland
2 Institute de Matemdticas Universidad Nacional Auténoma de Mézico Ciudad Universitaria, C.P. 04510, México, D.F., Mexico

Abstract

In this paper, we study \((2-d)\)-kernels in graphs. We shall show that the problem of the existence of \((2-d)\)-kernels is \(\mathcal{N}P\)-complete for a general graph. We also give some results related to the problem of counting \((2-d)\)-kernels in graphs. For special graphs, we show that the number of \((2-d)\)-kernels is equal to the Fibonacci numbers.